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Appliance Error Codes Database

Found 168 verified diagnostic error codes

All Categories ductless-mini-split — Daikin 15 and 19 Series furnace — York YP9C modulating condensing gas furnaces documented in the York installation manual controls-thermostats — ATW-RTU room thermostats paired with ATW-IOT-01 on Yutaki systems ductless-mini-split — Gree residential mini-splits that publish E5 in the protection code family controls-thermostats — Bryant Evolution communicating systems using the Evolution Connex control and a four-conductor communication bus controls-thermostats — Google Nest Learning Thermostat and Nest Thermostat furnace — York Affinity YP9C modulating condensing furnaces and the TP9C, CP9C and LP9C models sharing the same installation manual boiler — Baxi and Potterton domestic boilers that display E119 controls-thermostats — Google Nest thermostats covered by the E-code power guide controls-thermostats — Google Nest learning and programmable thermostats that report power and delay conditions on screen ductless-mini-split — Mitsubishi Electric indoor units publishing the P-series fault table, including M-Series wall units and Mr Slim indoor equipment heat-pump — XP17 heat pumps with iComfort communicating controls ductless-mini-split — MRCOOL DIY mini-split generations that report an inverter compressor drive fault ductless-mini-split — Panasonic wall-mounted split systems that report H-series and F-series self-diagnosis codes heat-pump — Altherma 3 R MT with ELBH-E or ELBX-E and ERRA08-12 furnace — Rheem residential gas furnaces covered by the published technical FAQ furnace — R96V communicating condensing gas furnaces ductless-mini-split — Daikin indoor units covered by the SM-TS3 malfunction chart, including room air, SkyAir, and VRV indoor equipment ductless-mini-split — WindFree 3.0 AR C ductless-mini-split — Bosch Climate 5000 ductless mini-split systems documented in the Bosch service and manual library ductless-mini-split — BMKH floor-ceiling indoor units ductless-mini-split — Midea wall-split systems, and systems built on the same platform sold under other names, that publish E2 furnace — Goodman GMVC-series two-stage variable-speed gas furnaces documented in the installation and operating instructions ductless-mini-split — Diamante and Quantum systems in the manufacturer code list boiler — Vaillant ecoTEC gas boilers covered by the Vaillant United Kingdom fault code list ductless-mini-split — Mitsubishi Electric indoor units that publish the P-series protection table, including Mr Slim cassette, ducted, and ceiling-suspended indoor units heat-pump — LG residential air conditioners covered by the United States help-library article grouping these codes as outdoor compressor or circuit board problems ductless-mini-split — Daikin indoor units covered by the SM-TS3 malfunction code chart, spanning room air, SkyAir, and VRV indoor equipment multi-zone — LG multi-split systems where several indoor units share a single outdoor unit, as described in LG help-library guidance ductless-mini-split — LG single-zone systems in MFL41161610 ductless-mini-split — Senville LETO Series ductless-mini-split — Diamante Essenza, Diamante Pro, Quantum Fresh, Hyperformance, and Ultra heat-pump — Stiebel Eltron WPL air source heat pumps commissioned through the manufacturer parameter set ductless-mini-split — Hisense residential split air conditioners documented in the Hisense service and document library boiler — Vaillant ecoTEC gas boilers covered by the published United Kingdom fault code list ductless-mini-split — Midea residential split air conditioners covered by the Midea online troubleshooting code reference heat-pump — Gree residential inverter systems covered by the OEM guide furnace — Carrier deluxe two-stage gas-fired induced-combustion furnaces with PSC or ICM blower motors, per troubleshooting guide 58-3T ductless-mini-split — Della ductless mini-split systems documented in the Della manual and support library Dishwasher LaserJet Printer ductless-mini-split — Mr Slim families covered by Mitsubishi Electric's P8 reference ductless-mini-split — Multi21+ and documented residential mini-splits ductless-mini-split — Daikin multi-split systems and splits that publish UF for a wiring and piping combination fault boiler — Ideal Logic and Vogue gas boilers using the F-series and L-series fault codes published by Ideal Heating ductless-mini-split — Daikin split and multi-split systems that publish UA for an indoor and outdoor combination fault air-handler — Goodman and Amana variable-speed air handlers with an integrated control module reporting motor codes on a seven-segment display and through a ComfortNet thermostat ductless-mini-split — MRCOOL DIY ductless systems across the third, fourth, and fifth generations documented in MRCOOL support controls-thermostats — ecobee smart thermostats with installer settings governing staging, thresholds, and equipment lockouts controls-thermostats — Drayton Wiser multi-zone heating systems using a heat hub with room thermostats and smart radiator thermostats ductless-mini-split — MRCOOL single-zone and multi-zone families in official support ductless-mini-split — Gree residential mini-split indoor units using the F-series sensing bulb codes described in Gree North America support boiler — Ideal Logic, Logic Max, and Logic Plus boilers that display F1 Air Conditioner heat-pump — Mitsubishi Electric outdoor units publishing the U-series fault table, including M-Series and MXZ multi-zone outdoor equipment boiler — Ideal Logic and Logic Max boilers covered by the published fault code guidance ductless-mini-split — Econo IF, Vario TL, and Optima TP single zone, and the multi-zone systems sharing the table ductless-mini-split — Daikin room air conditioner splits and multi-split systems that publish U0 in the malfunction code table controls-thermostats — tado Smart Radiator Thermostat V3+ and earlier devices in the cited support flow ductless-mini-split — Panasonic room air conditioners with the self-diagnosis function described in Panasonic service documentation ductless-mini-split — LG single-zone systems in general service manual MFL41161610 ductless-mini-split — Sophia multi-zone cassette indoor units furnace — GMVC80 condensing gas furnaces boiler — Ariston Clas gas boilers whose fault codes are grouped by leading digit in the Ariston user documentation furnace — Carrier two-stage and variable-speed modulating condensing furnaces that report status code 31 furnace — Goodman and Amana gas furnaces with an integrated ignition control that flashes seven for low flame signal furnace — Affinity YP9C modulating gas furnaces boiler — Viessmann Vitodens gas condensing boilers whose displayed fault codes are listed in the Viessmann fault checker ductless-mini-split — Mitsubishi Electric indoor units that publish the P-series fault table, covering Mr Slim and M-Series indoor equipment ducted-split — Carrier Infinity System Control paired with communicating equipment, with the outdoor-unit code structure documented for 24VNA6 and 25VNA4 variable-speed units heat-pump — Midea residential split air conditioners and heat pumps covered by the Midea online troubleshooting code reference ductless-mini-split — LG residential air conditioners covered by the United States help-library article that groups these codes as sensor problems boiler — Greenstar Si Compact ErP furnace — Ruud gas furnaces whose integrated controls report diagnostics through a blinking indicator, including the R96T range furnace — R96T two-stage communicating condensing furnaces controls-thermostats — Lennox iComfort communicating thermostats and the equipment controls they are paired with boiler — Worcester Bosch Greenstar boilers that pair E9 with cause code 219 ductless-mini-split — Samsung indoor air conditioner units whose display shows the reminder and operating-mode characters described in Samsung support ductless-mini-split — Econo, Vario, Optima, Motto, and Umbra mini-splits heat-pump — Hitachi Yutaki air-to-water heat pump systems documented in the Hitachi air-to-water installation and operation manuals heat-pump — NIBE air source and ground source heat pumps with controllers that store an alarm log and operating history boiler — Current ecoTEC plus boilers covered by manual 0020308121-04 ductless-mini-split — Pioneer Diamante and Quantum ductless systems whose code lists are published in Pioneer support ductless-mini-split — Panasonic reverse-cycle wall split systems that report F11 in the self-diagnosis table air-handler — Trane air handlers and indoor coils fitted with a condensate overflow switch, as described in Trane homeowner support boiler — Ariston Clas ONE, Clas System ONE, and Alteas ONE boilers showing 108 ductless-mini-split — KSIV Series ductless-mini-split — Senville ductless mini-split systems across the Aura, Leto, and earlier series documented in Senville support ductless-mini-split — Toshiba residential and light-commercial systems fitted with a wired remote controller controls-thermostats — Rheem and Ruud EcoNet communicating systems in which a smart thermostat or control center shares a four-wire network with indoor and outdoor equipment boiler — Logic Max Combi boilers in manual 237660 A01 ductless-mini-split — GE Zoneline packaged terminal air conditioners and heat pumps documented in GE Appliances owner and support material ductless-mini-split — Mitsubishi Heavy Industries room air conditioners documented in the MHI user manual library controls-thermostats — tado Smart Radiator Thermostat ductless-mini-split — Fujitsu General residential indoor units that report faults through operation and timer indicator lamps furnace — Trane gas furnaces whose integrated control proves flame by rectification, as described in Trane homeowner support for a burner that shuts off after ignition heat-pump — Yutaki hydronic heat-pump systems ductless-mini-split — Klimaire ductless mini-split systems documented in the Klimaire service and support library heat-pump — F2120 air-to-water heat pumps heat-pump — Daikin outdoor units covered by the SM-TS3 malfunction chart, including room air, SkyAir, and VRV outdoor equipment Washing Machine furnace — York YP9C, TP9C, CP9C, and LP9C furnaces covered by the cited manual ductless-mini-split — Mitsubishi Electric Mr Slim and M-Series systems that publish the P-series protection table multi-zone — LG multi-split systems where several indoor units share one outdoor unit controls-thermostats — tado smart thermostat systems using a wireless receiver or an extension kit between the control and the heating appliance ductless-mini-split — TCL residential split air conditioners documented in the TCL product download library ductless-mini-split — Hi-Ultra Xtreme R-454B furnace — Carrier deluxe two-stage gas-fired induced-combustion furnaces with PSC or ICM blower motors, as covered by troubleshooting guide 58-3T heat-pump — Daikin outdoor equipment covered by the SM-TS3 malfunction chart, spanning room air, SkyAir, and VRV outdoor units ductless-mini-split — Mitsubishi Electric M-Series and Mr Slim systems that publish the E-series communication table ductless-mini-split — Forward Series systems in the manufacturer service manual boiler — Clas One and Clas System One condensing gas boilers ductless-mini-split — Climate 5000 Generation 3 R-454B multi-zone ductless-mini-split — KSIO series systems in the manufacturer troubleshooting manual furnace — Goodman and Amana single-stage and two-stage gas furnaces with an integrated ignition control boiler — Vaillant ecoTEC plus and ecoTEC sustain boilers that list F.22 ductless-mini-split — Daikin indoor units covered by the SM-TS3 malfunction chart, where the C division covers sensor systems furnace — Rheem R96V modulating condensing gas furnaces documented in the Rheem service literature ductless-mini-split — Senville systems covered by the manufacturer EC 51 support article ductless-mini-split — Cooper and Hunter ductless mini-split systems documented in the Cooper and Hunter support library furnace — S9V2 S-Series two-stage condensing gas furnaces ductless-mini-split — Forward Series light-commercial — SkyAir RZR-P and RZQ-P(9) light-commercial — Amana PTAC models covered by the M70 service procedure ductless-mini-split — MRCOOL mini-splits covered by official P0/PC00 support furnace — Carrier 58MCB Series 110 and 120 condensing gas furnaces ductless-mini-split — LETO and AURA models using an applicable AC fan motor boiler — Baxi domestic gas boilers using the E-series fault codes listed in Baxi support material ductless-mini-split — MRCOOL generations and models identified in official support furnace — Goodman GMVC80 condensing gas furnaces heat-pump — Grant Aerona air source heat pumps documented in the Grant fault and support material heat-pump — Ecodan FTC5 cylinder units, EHPT20X-MHCW and EHST20(D)(C)-MHCW boiler — Vitodens 100-W heat-only boilers in the cited UK installation instructions multi-zone — Climate 5000 Generation 3 R-454B multi-zone outdoor units heat-pump — Trane TruComfort variable-speed outdoor units on ComfortLink II communicating controls, including the XV20i heat pump ductless-mini-split — Amana packaged terminal air conditioners and heat pumps covered by the Amana PTAC service literature controls-thermostats — Honeywell Home T6 programmable thermostats configured through installer setup parameters controls-thermostats — Lennox communicating systems on iComfort S30, E30 and compatible displays, covering furnaces, air handlers, outdoor units, equipment interface modules and iHarmony zoning heat-pump — Daikin equipment covered by the SM-TS3 malfunction chart, where the U division reports system-level conditions across room air, SkyAir, and VRV furnace — Goodman GMVC-series and related integrated furnace controls documented in the installation and operating instructions heat-pump — Mitsubishi Electric inverter outdoor units publishing the U-series fault table, including M-Series single-zone and MXZ multi-zone equipment controls-thermostats — Hive heating control systems using a hub, a thermostat, and a boiler receiver as described in Hive support multi-zone — Multi21+ and the residential ranges in the Gree code overview ductless-mini-split — Discontinued Quantum WYS, CYB, RYB, UYB, and FYB heat-pump — Daikin Altherma air-to-water heat pump systems serving space heating and a domestic hot water cylinder furnace — American Standard gas furnaces whose integrated controls retain a stored fault history alongside the current status boiler — Baxi domestic boilers covered by the manufacturer E133 guidance ductless-mini-split — Blueridge BMKH ductless mini-split systems documented in the Blueridge manual library ductless-mini-split — Aurora Xtreme Inverter 36,000 BTU cooling-only 220 V heat-pump — Aquarea air-to-water heat pumps ductless-mini-split — Samsung indoor air conditioner units that display the C1 group of service codes described in Samsung support material furnace — Carrier deluxe two-stage gas-fired induced-combustion furnaces with PSC or ICM blower motors, covered by troubleshooting guide 58-3T ductless-mini-split — Toshiba air conditioning equipment using the fault code tables published in the Toshiba United Kingdom technical handbook ductless-mini-split — Haier residential split air conditioners documented in the Haier service and resource library boiler — Worcester Bosch Greenstar gas boilers using the two-part display and fault code convention described in Worcester service instructions ductless-mini-split — Friedrich Floating Air ductless indoor units documented in the Friedrich product resource library
10, 31, 39 ProfessionalRequired
Lennox • controls-thermostats — Lennox communicating systems on iComfort S30, E30 and compatible displays, covering furnaces, air handlers, outdoor units, equipment interface modules and iHarmony zoning

Lennox iComfort alerts 10, 31 and 39 that keep coming back: tracing intermittent faults without swapping parts

Only one of the three is a communication code. Alert 31 reports that a component has not communicated with the thermostat for more than three minutes, and Lennox documents it as clearing once communication is restored. Alert 10 reports that an unknown device was found on the bus and needs configuring, not repairing. Alert 39 is a consequence: the system could not turn cooling on for more than 45 minutes, so it takes itself off-line for 60 minutes and retries. Replacing a control to chase 39 replaces the wrong thing. Applies to: Lennox communicating systems on iComfort S30, E30 and compatible displays, covering furnaces, air handlers, outdoor units, equipment interface modules and iHarmony zoning These entries come from the Lennox residential communicating systems alert table used with iComfort S30 and E30 displays. Lennox equipment running on a conventional 24 volt thermostat does not use this table, and legacy control-board flash patterns on the same appliance carry unrelated meanings. Owner-safe checks: Record the date, time and outdoor conditions each time an alert appears, and keep the list rather than clearing it. | Look for standing water or a slow drain at the indoor unit, because a float switch in series with the R terminal interrupts communication when it lifts. | Photograph any seven-segment display on the equipment, including a double horizontal line, before power is interrupted. Qualified technician: Voltage and continuity measurement at a communicating control is energised low-voltage work for a qualified technician. | Reconfiguration through the installer control center, and any isolation of devices on the bus one at a time, belongs to the installing contractor.

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P4 ProfessionalRequired
Klimaire • ductless-mini-split — KSIO series systems in the manufacturer troubleshooting manual

Klimaire P4: one indoor code, three outdoor LED patterns

P4 is an inverter compressor drive error. On the documented KSIO models the outdoor board publishes three different green and red LED combinations that all display as P4 indoors, so the outdoor board is carrying detail the indoor display does not. Applies to: KSIO series systems in the manufacturer troubleshooting manual The LED table here is published for KSIO009-H124-I and KSIO012-H123-I in the Klimaire troubleshooting manual. Klimaire documents its series separately, and the KSIA, KSIV, and KDIP families each have their own tables, so confirm the model on the outdoor plate before using this page. Owner-safe checks: Photograph the indoor display showing P4, and note the time and the mode the system was in. | Observe the outdoor indicator lamps from outside the cabinet and record which are lit or flashing. | Record the outdoor model number from the data plate, since the LED table is published per model. Qualified technician: The manual states it is for use by a certified service technician and warns that capacitors hold charge after the supply is switched off. | Drive diagnosis, module testing, and compressor measurement all require the cabinet open with the bus discharged, which is technician work.

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Indoor and outdoor groups ProfessionalRequired
Klimaire • ductless-mini-split — Klimaire ductless mini-split systems documented in the Klimaire service and support library

Klimaire codes: which half of the system is speaking

Klimaire documents its codes in groups that separate indoor conditions from outdoor ones, and that split is the first thing to use. Knowing which half raised the condition tells you where a technician will work and what class of repair is likely, before any exact entry has been found. Applies to: Klimaire ductless mini-split systems documented in the Klimaire service and support library Klimaire publishes service documentation per series, and the KSIV and KSIO lines carry their own tables. The document matching the model number on the data plate is the mapping, and a chart labelled with the brand alone can describe a different series. Owner-safe checks: Photograph the displayed code and both data plates before contacting anybody or interrupting power. | Note whether the outdoor unit runs at all, which is observable from a safe distance and separates the two groups immediately. | Record whether the fault has been present since installation or developed after a period of normal service. Qualified technician: Outdoor-side conditions involve the sealed refrigerant circuit and the drive, both of which require certification and the appropriate instruments. | Indoor casings carry the supply to the board and the fan motor, so opening one is qualified work even where the component behind the code is small.

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E1 ProfessionalRequired
Klimaire • ductless-mini-split — KSIV Series

Klimaire KSIV E1 indoor-outdoor communication error

Klimaire's KSIV troubleshooting literature defines E1 as an indoor-to-outdoor communication error. The code covers the complete path, including terminal order, installed cable, electrical supply, and the transmitting and receiving circuits; it does not independently diagnose a control board. Applies to: KSIV Series Use this meaning only for Klimaire KSIV systems within the cited service literature. KSIA, KDIP, and other Klimaire platforms can use different diagnostic tables even when an indoor display looks similar. Owner-safe checks: Capture E1, both complete model labels, first-occurrence timing, and any externally visible cable damage without opening an electrical panel. Qualified technician: Terminal inspection, cable testing, supply verification, signal measurement, and control-board diagnosis require a qualified KSIV technician.

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L2 ProfessionalRequired
Ideal Heating • boiler — Logic Max Combi boilers in manual 237660 A01

Ideal Logic Max L2 flame-loss lockout

On the documented Ideal Logic Max Combi, L2 is a flame-loss lockout. It records failure to establish or retain valid flame through the supervised sequence; it does not prove a dirty electrode. Gas pressure, valve command, spark, electrode and lead, condensate, flue, flame signal, and control require qualified tests. Applies to: Logic Max Combi boilers in manual 237660 A01 This L2 interpretation is limited to Logic Max Combi models covered by Ideal manual 237660 A01. Vogue, older Logic, Logic Air, and commercial Ideal appliances use their own fault tables. Owner-safe checks: Save L2, the model, other gas-appliance status, and audible startup sequence from outside the sealed case without forcing repeated ignition. Qualified technician: Gas pressure, valve, spark, electrode, flame-current, combustion, flue, condensate, wiring, and sealed-case work require a Gas Safe registered engineer.

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L1 ProfessionalRequired
Ideal Heating • boiler — Ideal Logic and Logic Max boilers covered by the published fault code guidance

Ideal L1 and L3: overheat and no water flow are not the same fault

Ideal publishes L1 as flow temperature overheat or no water flow and L3 as no water flow. For L1, Ideal says to open all radiator valves, confirm 1 to 1.5 bar, and reset. Its L3 guidance includes checking pressure and bleeding air from radiators. Record the exact code because the published wording and checks are not identical. Applies to: Ideal Logic and Logic Max boilers covered by the published fault code guidance These are Ideal Heating's published codes for its Logic and Logic Max ranges. Ideal also publishes an F-series in parallel, so an F1 on the same appliance is low pressure rather than an overheat. A letter and a number read from another manufacturer's boiler carries no relationship to these definitions. Owner-safe checks: Walk the house and open user-operated radiator valves and thermostatic heads; do not alter lockshield balancing valves. | Read the pressure gauge cold and top up to the 1 to 1.5 bar band Ideal names if it is low. | Bleed radiators that are cold at the top, then recheck the pressure afterwards. | Reset the boiler once after making a change, and observe a full heating cycle before deciding. | Note which radiators stay cold and where they are in the house before calling for service. Qualified technician: L1 or L3 returning after every valve is open, the pressure is correct, and the radiators have been bled. | An L5 code, which indicates the boiler has been reset too many times rather than diagnosing the original fault. | Any suspicion of a circulation pump fault or a blocked circuit, both of which need the casing opened. | Radiators that stay cold at the bottom, which points at debris in the system rather than at air. | Pressure that will not hold after topping up, which is a separate fault running alongside this one.

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F2 ProfessionalRequired
Ideal Heating • boiler — Ideal Logic and Vogue gas boilers using the F-series and L-series fault codes published by Ideal Heating

Ideal F2: the flame was there and then it was not

Ideal uses F2 for a flame loss condition, which is a different event from a failure to establish flame at all. The burner lit, ran, and then the appliance stopped detecting combustion, so the investigation starts from what changed during operation rather than from what prevented ignition. Applies to: Ideal Logic and Vogue gas boilers using the F-series and L-series fault codes published by Ideal Heating Ideal publishes separate fault code lists for its Logic, Logic Max, and Vogue ranges, and the same character can carry different detail across them. Take the code from the display of the appliance in front of you and check it against the Ideal literature for that model rather than a general list. Owner-safe checks: Time how long the boiler runs before the fault appears, and note whether heating or hot water was actually produced. | Record which other gas appliances were in use each time the fault occurred. | Note whether failures happen on small demands, large demands, or both, since the pattern is diagnostic. Qualified technician: Measuring working gas pressure, testing the flame signal, and inspecting the flue and condensate arrangement are Gas Safe registered tasks. | If gas can be smelled, that single fact outranks the fault code entirely. Get everyone out, touch no switches, and telephone the emergency line for your supplier once you are outside.

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F1 ProfessionalRequired
Ideal Heating • boiler — Ideal Logic, Logic Max, and Logic Plus boilers that display F1

Ideal Logic F1 fault code: what low water pressure means

Ideal defines F1 as low water pressure in the sealed heating system, and the boiler stops until the pressure is raised. Ideal tells the owner to check the gauge reads between 1 and 1.5 bar and to repressurise with the filling loop if it is low, then to call a Gas Safe registered engineer if the pressure keeps dropping. Applies to: Ideal Logic, Logic Max, and Logic Plus boilers that display F1 This applies to Ideal Logic family boilers whose published fault guidance lists F1. Ideal uses L1 for a flow overheat or no-flow condition, which is a different branch, so read the exact characters on the display before acting. Owner-safe checks: With the boiler off and cool, read the pressure gauge and top up to about 1.5 bar with the filling loop only if it is below 1 bar. | After topping up, close both filling-loop valves fully and check whether the pressure holds over the next day of normal heating. Qualified technician: A pressure that will not hold, visible leaks or staining, an expansion vessel check, or an F1 that alternates with L1 needs a Gas Safe registered engineer.

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No heat demand ProfessionalRequired
Honeywell Home • controls-thermostats — Honeywell Home T6 programmable thermostats configured through installer setup parameters

Honeywell T6 not calling for heat: installer settings before faults

A Honeywell T6 that shows a set point above the room temperature and still produces no heat is either being prevented by a configuration parameter or is not connected to what it thinks it is. Installer setup decides system type, staging, changeover, and minimum off times, and each of those can suppress a demand that looks perfectly reasonable on screen. Applies to: Honeywell Home T6 programmable thermostats configured through installer setup parameters T6 covers wired and wireless variants across several markets, with installer setup parameters that differ between them. The installer setup guide for the exact T6 variant you own is the reference, and a parameter number from a different variant can select something else entirely. Owner-safe checks: Confirm the time, the day, and the schedule on the thermostat, and check whether a hold or a temporary override is active. | Raise the set point by hand and note whether heat arrives, which separates scheduling from everything downstream. | On a wireless variant, look at the receiver near the appliance and note whether it indicates a demand. Qualified technician: Installer setup parameters govern which terminals are energised and how equipment is staged, and selecting the wrong system type can make a thermostat energise a circuit the equipment does not expect. | Terminals inside a boiler or a wireless receiver sit at mains potential in British installations, which puts any work on them outside what an occupant should attempt.

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No signal / offline ProfessionalRequired
Hive • controls-thermostats — Hive heating control systems using a hub, a thermostat, and a boiler receiver as described in Hive support

Hive not controlling the boiler: three links that can break separately

A Hive installation is a chain: the app talks to Hive, Hive talks to the hub, the hub talks to the thermostat and the receiver, and the receiver switches the boiler. A break anywhere along that chain presents in the app as the heating not responding, and the repair depends entirely on where the break is. Applies to: Hive heating control systems using a hub, a thermostat, and a boiler receiver as described in Hive support Hive has shipped several generations of hub, thermostat, and receiver with different radio arrangements and different indications. The Hive support material for the products you actually own is the reference, and the position of a break is established from the devices rather than from the app alone. Owner-safe checks: Operate the manual or boost control on the receiver and note whether the boiler responds, which splits the fault in half immediately. | Check whether the thermostat still controls the heating locally even if the app cannot reach the system. | Note anything that changed in the house recently: a new router, a moved hub, an appliance, or building work. Qualified technician: Wiring between a receiver and a heating appliance carries mains voltage on United Kingdom installations and is not an owner task. | A boiler that does not respond to manual operation at the receiver is a heating fault rather than a connectivity one, and it belongs to a Gas Safe registered engineer.

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Alarm groups ProfessionalRequired
Hitachi • heat-pump — Hitachi Yutaki air-to-water heat pump systems documented in the Hitachi air-to-water installation and operation manuals

Hitachi Yutaki alarms: the water side and the refrigerant side are different jobs

A Yutaki system has two fluid circuits that can each raise alarms: a refrigerant circuit between the outdoor unit and the heat exchanger, and a water circuit serving the house. Knowing which side an alarm belongs to decides almost everything that follows, including whether the work is certified refrigerant handling or ordinary heating pipework. Applies to: Hitachi Yutaki air-to-water heat pump systems documented in the Hitachi air-to-water installation and operation manuals Yutaki covers split, monobloc, and high-temperature configurations, and the alarm set differs between them as well as between generations of the controller. Read the alarm against the installation and operation manual for your exact configuration rather than a general Hitachi list. Owner-safe checks: Photograph the controller showing the alarm number and any accompanying text before anyone resets it. | Record the outdoor temperature, the flow temperature the controller was asking for, and whether hot water is also affected. | Check the system pressure on the heating circuit and note the reading while the system is cold. Qualified technician: Any alarm belonging to the refrigerant circuit requires a certified refrigerant handler under F-Gas rules in the United Kingdom and European Union, or EPA Section 608 in the United States. | Water-side work on a heat pump, including pump settings and circuit balancing, should be carried out by an engineer familiar with heat pump flow rates rather than boiler practice.

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77 / 78 ProfessionalRequired
Hitachi • controls-thermostats — ATW-RTU room thermostats paired with ATW-IOT-01 on Yutaki systems

Hitachi Yutaki alarms 77 and 78: the radio link, not the heat pump

Both alarms are about communication rather than heating. Alarm 77 means the Yutaki unit has lost communication with the ATW-IOT-01 interface, and alarm 78 means communication between ATW-IOT-01 and the ATW-RTU-12 thermostat has failed. Applies to: ATW-RTU room thermostats paired with ATW-IOT-01 on Yutaki systems These alarm numbers belong to the ATW-RTU room thermostat and the ATW-IOT-01 interface on Yutaki systems, as published in the Hitachi installation and operation manual for those controls. Yutaki units raise their own alarms in their own numbering, and a number seen on a wired controller is not necessarily the same number seen on the room thermostat. Owner-safe checks: Record the alarm exactly, including any decimal, and note which display you read it on. | Confirm the ATW-IOT-01 interface is powered, which is the first check the manual lists for both alarms. | Note whether anything changed in the property recently, such as a new appliance, a partition, or a repositioned thermostat. Qualified technician: Wiring integrity, wire loops, and interference sources on the Yutaki to interface link are installer work rather than owner checks. | A repeating alarm 78.1 is assigned to the room thermostat hardware and the manufacturer response is replacement, which should be arranged rather than attempted.

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70 ProfessionalRequired
Hitachi • heat-pump — Yutaki hydronic heat-pump systems

Hitachi Yutaki alarm 70: no water flow detected

Hitachi's Yutaki technical guidance ties alarm 70 to an unsuccessful water-flow check. The alarm does not prove that the circulation pump failed: a blocked hydraulic route, closed valve, clogged filter, air, low water condition, pump problem, or flow detection issue can all prevent confirmed circulation. Applies to: Yutaki hydronic heat-pump systems This definition is limited to Hitachi Yutaki heating systems covered by the cited manufacturer technical tip. A two-digit Hitachi alarm on an air-conditioning or Set Free controller may have a different scope. Owner-safe checks: Record the alarm, model, requested mode, visible controller pressure, recent hydraulic work, and external leakage without opening the appliance. Qualified technician: Flow measurement, pump tests, filter access, air removal, valve diagnosis, and electrical sensing checks require the Yutaki installer or service engineer.

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Sensor group ProfessionalRequired
Hisense • ductless-mini-split — Hisense residential split air conditioners documented in the Hisense service and document library

Hisense sensor codes: when the number identifies a reading, not a part

Hisense sensing codes report that a temperature reading has left the range the control will act on. Every one of them describes a measurement rather than a component, which is why the same code covers a failed element, a disconnected plug, and a corroded terminal without distinguishing between them. Applies to: Hisense residential split air conditioners documented in the Hisense service and document library Hisense publishes documentation by product family rather than as one brand-wide list, and code assignments differ between the residential ranges. The service document for the model on your data plate is the reference; a table gathered from another Hisense product may not transfer. Owner-safe checks: Photograph the indoor display showing the code before interrupting power for any reason. | Compare the temperature the unit reports with a thermometer and write both figures down. | Note any storm, flooding, pest activity, or outdoor work in the weeks before the fault appeared. Qualified technician: Measuring sensing resistance and inspecting connectors requires the indoor or outdoor casing to be opened, and the outdoor enclosure carries mains voltage as well as refrigerant pipework. | Do not attempt to dry, clean, or reseat an outdoor connector. Water ingress often accompanies damage that is not visible from outside the casing.

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16 ProfessionalRequired
Hisense • ductless-mini-split — Hi-Ultra Xtreme R-454B

Hisense Hi-Ultra Xtreme code 16 changes with operating mode

On the documented Hisense Hi-Ultra Xtreme 454B family, code 16 is mode-dependent: in cooling it reports indoor-coil antifreeze protection, while in heating it reports an overload protection condition. Record the active mode because the same number leads to a different diagnostic branch. Applies to: Hi-Ultra Xtreme R-454B This dual meaning belongs to the Hi-Ultra Xtreme R-454B service literature cited here. It must not be applied to Hisense portable appliances, dehumidifiers, other refrigerants, or unrelated ductless series. Owner-safe checks: Preserve the active mode, photograph code 16, inspect only accessible filters and clearances, and let visible ice thaw without tools or added heat. Qualified technician: Sensor, fan, refrigerant, pressure, wiring, and control-board tests require a technician using the Hi-Ultra Xtreme 454B service procedure.

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F11 / F28 ProfessionalRequired
Haier • ductless-mini-split — Forward Series systems in the manufacturer service manual

Haier Forward F11 and F28: compressor position not detected

Both codes report that the position of the compressor rotor cannot be detected normally. The service manual gives the decision conditions as compressor wiring that is wrong or poorly connected, or a damaged compressor, so the code covers a wide range of repair. Applies to: Forward Series systems in the manufacturer service manual This follows the Haier service manual for the Forward Series, where the codes appear as indoor display F11 and F28 alongside outdoor LED1 flash counts of 18 and 19. Haier assigns codes by product family, and the Forward Series is documented in its own literature, so confirm the range before applying these meanings. Owner-safe checks: Photograph the indoor display, or count two complete flash cycles at the outdoor board and write the number down. | Record whether any work has been done at the outdoor unit, and by whom, since the system last ran normally. | Note whether the outdoor fan turns at all when the system is asked to start, without opening any panel. Qualified technician: Compressor terminals, drive circuits, and winding measurements are technician work with the supply isolated and the capacitors discharged. | Ask for the compressor to be tested rather than inferred, because the manual lists wiring and a damaged compressor as alternatives under the same code.

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E7 ProfessionalRequired
Haier • ductless-mini-split — Forward Series

Haier Forward Series E7 communication fault

On Haier Forward Series systems, indoor code E7 identifies a communication failure between the indoor and outdoor units; the outdoor diagnostic can report the same condition with 15 flashes. Wiring, connections, supply, and either control end remain candidates until the communication path is tested. Applies to: Forward Series This definition comes from Haier's North American Forward Series service manual. Other Haier families reuse E7 for different conditions, so the series and both model labels must match before this meaning is applied. Owner-safe checks: Save the indoor display, both rating plates, whether the system ever ran, and the timing of any outage, storm, installation, or repair. Qualified technician: Outdoor flash observation behind a cover, cable tests, terminal correction, voltage measurement, and board diagnosis belong to qualified service.

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E5 ProfessionalRequired
Haier • ductless-mini-split — Haier residential split air conditioners documented in the Haier service and resource library

Haier E5: overcurrent stops are as much about the supply as the unit

Haier uses E5 for an overcurrent condition, meaning the current drawn exceeded what the control permits. Current is a product of the work being demanded and the voltage available to do it, so a low or unstable supply produces the same code as a compressor that is hard to turn. Applies to: Haier residential split air conditioners documented in the Haier service and resource library This applies to Haier residential split equipment documented in the Haier service library. Haier manufactures for several brand programmes, and units sold under other names may use a different code set even where hardware overlaps. Confirm against the manual issued with your own unit. Owner-safe checks: Make one start attempt and note how long the outdoor unit runs before the code returns. | Watch whether household lighting reacts at the moment of start, and note the time of day each occurrence happens. | Confirm no protective device in the consumer unit or panel has operated, and that the unit is on the supply arrangement it was installed with. Qualified technician: Measuring supply voltage under starting load, testing compressor windings, and assessing the drive are energised tasks for a qualified person. | A protective device that trips when the unit starts, a burning smell, or heat at an isolator means leaving the supply off and arranging an electrical inspection before anything else.

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H5 ProfessionalRequired
Gree • heat-pump — Gree residential inverter systems covered by the OEM guide

Gree H5 error code: intelligent power module protection

Gree identifies H5 as intelligent power module protection caused by an IPM synchronization or overcurrent condition; the protection can have airflow, refrigerant, wiring, board, or compressor causes. Applies to: Gree residential inverter systems covered by the OEM guide H5 as described here follows the Gree technical guide for residential inverter systems. Protection codes are tied to a specific drive design, so confirm the service manual for your model before treating this as the definition, and never assume a Gree code carries across to another manufacturer. Owner-safe checks: Turn the system off and look for a blocked return filter or obvious debris restricting the outdoor coil. | Record whether H5 appears immediately or only after the compressor begins operating. Qualified technician: Refrigerant pressure, compressor winding, DC bus, and live-voltage tests are technician work. | Do not replace a board or compressor until the root operating condition is confirmed.

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F2 ProfessionalRequired
Gree • ductless-mini-split — Gree residential mini-split indoor units using the F-series sensing bulb codes described in Gree North America support

Gree F2: losing the coil sensor removes the freeze protection

Gree assigns F2 to the indoor evaporator sensing bulb being open or short circuited. That bulb sits on the indoor coil rather than in the air stream, and its reading is what freeze protection and cold-draught prevention are built on, so the unit stops rather than run those functions without a value it can trust. Applies to: Gree residential mini-split indoor units using the F-series sensing bulb codes described in Gree North America support The F-series entries described here belong to Gree residential mini-split equipment. Equipment manufactured by Gree and sold under a partner brand can present its own code set and its own sensor arrangement, so match the code to the manual issued with your indoor unit rather than to the manufacturer behind it. Owner-safe checks: Select fan-only operation if ice is present and let the coil thaw without applying heat, water, or any tool to it. | Photograph any frost or ice before it melts, since the pattern of where it formed is useful to service. | Note whether heating had been slow to blow warm air in the weeks before the code appeared. Qualified technician: A bulb clamped to refrigerant tubing behind the front panel is not owner-accessible, and Gree assigns this class of fault to a licensed technician. | Repeated indoor coil icing needs airflow and refrigerant assessment, which is certified work rather than something to diagnose from the room.

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