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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 furnace — Rheem residential gas furnaces covered by the published technical FAQ heat-pump — Altherma 3 R MT with ELBH-E or ELBX-E and ERRA08-12 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 boiler — Vaillant ecoTEC gas boilers covered by the Vaillant United Kingdom fault code list ductless-mini-split — Diamante and Quantum systems in the manufacturer 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 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 — Daikin indoor units covered by the SM-TS3 malfunction code chart, spanning room air, SkyAir, and VRV indoor equipment 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 boiler — Ideal Logic and Vogue gas boilers using the F-series and L-series fault codes published by Ideal Heating ductless-mini-split — Daikin multi-split systems and splits that publish UF for a wiring and piping combination fault ductless-mini-split — Daikin split and multi-split systems that publish UA for an indoor and outdoor combination fault ductless-mini-split — MRCOOL DIY ductless systems across the third, fourth, and fifth generations documented in MRCOOL support 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 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 furnace — Ruud gas furnaces whose integrated controls report diagnostics through a blinking indicator, including the R96T range boiler — Greenstar Si Compact ErP 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 — NIBE air source and ground source heat pumps with controllers that store an alarm log and operating history heat-pump — Hitachi Yutaki air-to-water heat pump systems documented in the Hitachi air-to-water installation and operation manuals 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 controls-thermostats — tado Smart Radiator Thermostat ductless-mini-split — Mitsubishi Heavy Industries room air conditioners documented in the MHI user manual library 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 ductless-mini-split — Fujitsu General residential indoor units that report faults through operation and timer indicator lamps 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 controls-thermostats — tado smart thermostat systems using a wireless receiver or an extension kit between the control and the heating appliance multi-zone — LG multi-split systems where several indoor units share one outdoor unit 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 ductless-mini-split — Mitsubishi Electric M-Series and Mr Slim systems that publish the E-series communication table heat-pump — Daikin outdoor equipment covered by the SM-TS3 malfunction chart, spanning room air, SkyAir, and VRV outdoor units 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 ductless-mini-split — Forward Series furnace — S9V2 S-Series two-stage condensing gas furnaces 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 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 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 — 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 furnace — Goodman GMVC-series and related integrated furnace controls documented in the installation and operating instructions 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
F02 / E01 SafeUserCheck
Whirlpool • Washing Machine

Whirlpool Front-Load Washer F02 / E01: Long Drain Detected

Drain time exceeded 8 minutes; computer halts wash cycle and locks controls.

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OE SafeUserCheck
LG • Washing Machine

LG Washer OE Error Code: Drain Malfunction

Water level frequency does not decrease during the drain sequence.

Easy DIY View Guide →
E24 SafeUserCheck
Bosch • Dishwasher

Bosch Dishwasher Error Code E24: Drain Issue / Pump Blocked

The drain pump cannot expel wash water within expected cycle time due to blockage or kinked hose.

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12 red flashes ProfessionalRequired
York • furnace — Affinity YP9C modulating gas furnaces

York YP9C twelve red flashes: the ID plug is not connected

The manual assigns twelve red flashes to the ID plug not being present or not connected properly, and directs the check at a loose plug or loose wires in the plug. It is a connector fault, not a control board failure. Applies to: Affinity YP9C modulating gas furnaces This flash code is published in the York installation manual for the Affinity YP9C modulating gas furnaces. Other York furnace families use different control boards with different flash tables, and a twelve-flash code on another manufacturer's furnace means something unrelated. Owner-safe checks: Watch at least two complete flash groups and note both the colour and the count before recording it. | Record whether any work was done inside the furnace before the code appeared, and by whom. | Check that the furnace has power and that no breaker has tripped, without opening the cabinet. Qualified technician: The ID plug and the control board sit inside a cabinet containing gas piping and line voltage connections, so reseating or replacing the plug is technician work. | The manual warns against bypassing any safety control or adjusting a pressure switch to allow the furnace to run.

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7 red flashes ProfessionalRequired
York • furnace — Affinity YP9C modulating gas furnaces

York Affinity YP9C seven red flashes: ignition lockout

On the documented York Affinity YP9C, seven red flashes indicate lockout because ignition did not succeed after three attempts. The control waits one hour before another automatic attempt. The pattern reports the outcome, not whether the cause is gas supply, ignition, burner, flame sensing, grounding, venting, or control. Applies to: Affinity YP9C modulating gas furnaces This flash count is scoped to the YP9C manual cited here. York LX, Latitude, rooftop, heat-pump, and newer communicating controls can use other code systems, so the model and LED colour must match. Owner-safe checks: With panels closed, save the seven-red-flash pattern and observe one startup only through the factory viewing area without forcing another attempt. Qualified technician: Venting, pressure safeguards, ignition, gas, burners, flame current, grounding, combustion, and control testing require licensed York service.

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5 red flashes ProfessionalRequired
York • furnace — York YP9C modulating condensing gas furnaces documented in the York installation manual

York YP9C five red flashes: flame where the control did not ask for it

Five red flashes on a York YP9C control reports flame present at a time the control did not command it. That is a statement about the gas train rather than about ignition performance, so the furnace should be taken out of use and handed to a licensed engineer rather than reset and observed. Applies to: York YP9C modulating condensing gas furnaces documented in the York installation manual The flash table referenced here is the one published for the York YP9C modulating condensing furnace. York assigns flash counts differently across its furnace lines, and equipment from related brands on similar control platforms carries its own table, so the model on the rating plate governs. Owner-safe checks: Check for any smell of gas first, and if one is present leave the property and call the gas emergency number from outside before anything else. | Isolate the appliance using the service switch fitted beside it, which ends the cycling without touching anything inside the cabinet. | Write down whether continued warmth or burner activity was observed, and at what point in the cycle the flashes appear. Qualified technician: Gas valve testing, burner inspection, and flame sensing circuit measurement on a modulating condensing furnace are licensed gas engineering tasks. | Do not restore the furnace to service to see whether the code returns. A repeat cycle is the risk this code is warning about.

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4 red flashes ProfessionalRequired
York • furnace — York YP9C, TP9C, CP9C, and LP9C furnaces covered by the cited manual

York YP9C four red flashes: limit, sensor, or fuse

On the documented York YP9C control, four red flashes can mean an open high-limit switch, a defective temperature sensor, or an open 24-volt fuse. Confirm that the LED is red, not amber, before using that definition. Four amber flashes describes reduced heating capacity from restricted circulating airflow. Applies to: York YP9C, TP9C, CP9C, and LP9C furnaces covered by the cited manual This page covers the YP9C family and the TP9C, CP9C, and LP9C models named in the same York manual. The color is part of the code, and other York controls may assign a different meaning to four flashes. Owner-safe checks: Record the flash color and count through two complete groups without removing a furnace door. | With heating off, inspect the homeowner-access filter and confirm ordinary return and supply grilles are clear. | Note whether the thermostat display remains powered and whether the blower continues after the burners stop. Qualified technician: Fuse diagnosis, sensor testing, temperature-rise measurement, blower assessment, and safety-circuit work belong to qualified gas-furnace service. | Never bypass a limit or install a larger fuse. Either action removes the protection York intended the control to enforce.

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3 red flashes ProfessionalRequired
York • furnace — York Affinity YP9C modulating condensing furnaces and the TP9C, CP9C and LP9C models sharing the same installation manual

York YP9C three red flashes at low fire only: pressure switch, pressure sensor, or the vent

Three red flashes reports the pressure switch open with inducer pressure above the switch setpoint, meaning the switch is open when it should be closed. The reason this shows up at low fire is written into the same manual. The switch is mounted on the draft inducer and proves flow at the start of each cycle. The manual then states that it may be open under certain conditions when the burners are lit, because the pressure sensor on the control board is the primary flow sensor. Minimum firing rate is where inducer speed and the pressure the switch sees are both lowest. Applies to: York Affinity YP9C modulating condensing furnaces and the TP9C, CP9C and LP9C models sharing the same installation manual This applies to the modulating YP9C family and the models sharing its installation manual, which use both a pressure switch on the inducer and a separate pressure sensor on the control board. Single and two-stage York furnaces without that pressure sensor read a pressure switch fault differently. Owner-safe checks: Watch a full cycle through the door view port and note how many seconds pass between ignition and the fault. | Retrieve the stored error codes with no thermostat call active, and write them down in the order they replay. | Check that the outdoor vent and combustion air terminals are clear of snow, leaves and nests from outside the building. | Confirm the condensate drain is running freely, since a separate condensate pressure switch can shut the burners off. Qualified technician: Testing the pressure switch, its hoses and the pressure sensor means working inside the burner compartment on an energised appliance, which is service work. | Any assessment of the vent system, combustion air piping or the inducer belongs to a qualified technician, and pressure switches must never be adjusted to allow operation.

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2 red flashes ProfessionalRequired
York • furnace — York YP9C modulating condensing gas furnaces documented in the York installation manual

York YP9C two red flashes: the draft proving circuit did not behave

Two red flashes on a York YP9C control points at the draft proving circuit: the pressure switch has not reached the state the control expects for the stage of the sequence it is in. The count identifies the circuit, not the component, so the inducer, the vent path, the condensate arrangement, and the switch itself are all inside the reading. Applies to: York YP9C modulating condensing gas furnaces documented in the York installation manual This applies to the York YP9C modulating condensing furnace as documented in its installation manual. York uses different flash tables on other furnace lines, and a modulating furnace proves draft across more than one firing rate, which changes what a fault at a particular stage implies compared with a single-stage appliance. Owner-safe checks: Count the flashes carefully through the sight glass, keeping the blower door closed so control power is not interrupted. | Check the outdoor vent and intake terminations from ground level for snow, ice, nests, or plant growth without climbing or probing. | Note whether ignition is ever attempted and whether the fault is linked to a change in firing rate. Qualified technician: Measuring draft pressure, testing the inducer, clearing condensate traps, and verifying switch operation at each firing rate are licensed gas-furnace tasks. | Any indoor smell of combustion products, or a carbon monoxide alarm, means leaving the appliance off, getting fresh air into the space, and calling the gas emergency number before anything else.

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Fan fault group ProfessionalRequired
Worcester Bosch • boiler — Worcester Bosch Greenstar gas boilers using the two-part display and fault code convention described in Worcester service instructions

Worcester Greenstar fan faults: reading a code that has two halves

Worcester Greenstar boilers report faults as a display code and a fault code together, and the pair is what identifies the condition. Fan-related entries in that convention describe the appliance being unable to establish or confirm the fan speed it requires, which prevents combustion because gas is metered against the air the fan delivers. Applies to: Worcester Bosch Greenstar gas boilers using the two-part display and fault code convention described in Worcester service instructions Worcester uses the two-part convention across the Greenstar range but the specific pairing differs between models and generations. Record both parts exactly as the display shows them and match them against the service instructions for the model on your appliance data plate rather than a list compiled elsewhere. Owner-safe checks: Photograph the display so that both code elements are captured, along with anything else shown on screen. | Copy the full model name and serial number from the data plate, which is behind or beneath the casing flap on most Greenstar appliances. | Listen during one start attempt and note whether a fan is audible and for how long. Qualified technician: Diagnosing and replacing a boiler fan, and testing its wiring and feedback, are Gas Safe registered tasks on a room-sealed appliance. | The casing forms part of the sealed enclosure between combustion and the room, so it is not removed for inspection by an occupant.

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EA 227 ProfessionalRequired
Worcester Bosch • boiler — Greenstar Si Compact ErP

Worcester Greenstar Si Compact EA 227 ignition fault

On the documented Worcester Bosch Greenstar Si Compact ErP, EA with subcode 227 means no ionisation was detected after ignition. The user instructions permit the Reset button once and require service if the alert returns. The display does not prove whether flame failed to form or formed without valid sensing. Applies to: Greenstar Si Compact ErP This EA 227 definition is for Greenstar Si Compact ErP user instructions 6 720 813 279. Other Greenstar models attach different three-digit subcodes to EA, so record both lines of the display. Owner-safe checks: Photograph EA and 227 together, perform only the user-manual reset once, and note whether stable operation returns without opening the case. Qualified technician: Returning EA 227, gas, combustion, ionisation, electrode, vent, condensate, grounding, and sealed-case work require a Gas Safe registered engineer.

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E9 219 ProfessionalRequired
Worcester Bosch • boiler — Worcester Bosch Greenstar boilers that pair E9 with cause code 219

Worcester Bosch E9 219 fault code: heating safety overheat

Worcester Bosch assigns E9 with cause code 219 to the central heating safety temperature limiter having tripped, meaning the flow temperature at the heat exchanger climbed past its allowed limit. It points at heat not moving away from the exchanger fast enough, from a circulation, pump, or fouling problem, rather than at a single failed part. Applies to: Worcester Bosch Greenstar boilers that pair E9 with cause code 219 This reading follows Worcester Bosch Greenstar literature that displays a fault code alongside a cause code and lists 219 as the safety temperature limiter. Other Worcester ranges and other E9 cause codes can differ, so record both numbers together before acting. Owner-safe checks: Note both numbers, E9 and 219, and the time the lockout appeared, then leave the boiler switched off rather than cycling the reset. | Check that any labelled isolation valves under the boiler are open and in the same position as normal, without removing covers. Qualified technician: Pump, flow sensor, heat exchanger, safety limiter, and system flushing work all require a Gas Safe registered engineer, and the boiler should stay off until then.

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Burner lockout group ProfessionalRequired
Viessmann • boiler — Viessmann Vitodens gas condensing boilers whose displayed fault codes are listed in the Viessmann fault checker

Viessmann burner lockouts: what the fault checker can and cannot settle

A Viessmann burner lockout means the appliance attempted to establish combustion, failed to prove it within the permitted attempts, and stopped offering heat. Viessmann's own fault checker maps the displayed code to a condition, and the value of that tool is that it distinguishes lockouts from blocking faults, which behave and clear along different lines. Applies to: Viessmann Vitodens gas condensing boilers whose displayed fault codes are listed in the Viessmann fault checker The Vitodens range spans wall-hung combi, system, and floor-standing appliances across several generations, and code meanings are model-specific. Enter the code into Viessmann's own checker together with the appliance model rather than relying on a list that does not ask which boiler you have. Owner-safe checks: Photograph the display showing the code, then copy the full model name and serial number from the appliance data plate. | Record whether the boiler recovered on its own or needed a reset, and how many times each has happened. | Check the system pressure gauge while the system is cold and note the reading. Qualified technician: Gas pressure measurement, ignition and sensing component work, flue inspection, and condensate system correction are Gas Safe registered tasks. | A boiler that locks out again immediately after a reset should be left alone rather than reset repeatedly, because each attempt spends further ignition cycles against the same condition.

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59 ProfessionalRequired
Viessmann • boiler — Vitodens 100-W heat-only boilers in the cited UK installation instructions

Viessmann Vitodens 100-W fault 59: supply undervoltage

In the cited Viessmann Vitodens 100-W heat-only instructions, fault 59 is a burner lockout associated with power-supply undervoltage. The service response is to check the mains supply and, if the fault recurs, investigate the fan path. The code does not justify an owner changing the fan or boiler electronics. Applies to: Vitodens 100-W heat-only boilers in the cited UK installation instructions This definition is limited to the United Kingdom Vitodens 100-W heat-only manual cited below. Viessmann fault meanings differ across Vitodens generations, combination boilers, Vitocal heat pumps, and control platforms. Owner-safe checks: Save fault 59 and the model label, note building-wide power symptoms and power-source changes, and leave the boiler connection untouched. Qualified technician: Live mains, boiler connection, fan, harness, control, combustion, and sealed-case checks require a qualified electrician or Viessmann heating engineer.

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F.75 ProfessionalRequired
Vaillant • boiler — Current ecoTEC plus boilers covered by manual 0020308121-04

Vaillant ecoTEC plus F.75: pressure rise not detected

On the documented Vaillant ecoTEC plus, F.75 means the control did not detect sufficient heating-water pressure change when the pump started. The service list includes low fill pressure, air or insufficient water, expansion-vessel influence, pump or pressure-sensor faults, and their wiring; neither component is proven by the code. Applies to: Current ecoTEC plus boilers covered by manual 0020308121-04 This meaning follows current ecoTEC plus installation and maintenance instructions 0020308121-04. Older ecoTEC generations, commercial boilers, aroTHERM heat pumps, and regional variants require their own document. Owner-safe checks: Photograph F.75 and the visible pressure, note recent bleeding or filling, and inspect only accessible external pipework for water. Qualified technician: Pump, pressure-sensor, expansion-vessel, filling, venting, internal leak, wiring, gas, and sealed-case work requires a qualified heating engineer.

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F.32 ProfessionalRequired
Vaillant • boiler — Vaillant ecoTEC gas boilers covered by the Vaillant United Kingdom fault code list

Vaillant F.32: no fan means no combustion, by design

Vaillant gives F.32 as the fan being faulty or not connected. On a room-sealed condensing boiler the fan is what draws combustion air in and pushes flue gases out, so the appliance cannot burn gas safely without it. The lockout is not the boiler being cautious; it is the only acceptable response to losing forced draught. Applies to: Vaillant ecoTEC gas boilers covered by the Vaillant United Kingdom fault code list This definition comes from Vaillant's fault code list for ecoTEC appliances in the United Kingdom. The same number means something else on other manufacturers and on some Vaillant ranges outside the ecoTEC family, so read it against the list printed inside the casing flap of your own boiler. Owner-safe checks: Listen at the start of an attempt and note whether any fan sound occurs at all, and whether it sounds as it used to. | Record the exact code and how many attempts produce the same result before you stop trying. | Check whether any recent service, part replacement, or electrical work preceded the fault. Qualified technician: Testing, cleaning, or replacing a boiler fan and its wiring is Gas Safe registered work on a sealed combustion appliance in the United Kingdom. | Resist the urge to take the front panel off for a look. On a room-sealed appliance that panel is a safety component, and opening it breaks the separation it exists to maintain.

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F.28 ProfessionalRequired
Vaillant • boiler — Vaillant ecoTEC gas boilers covered by the published United Kingdom fault code list

Vaillant F.28 and F.29: two ignition faults with one owner check

Vaillant defines F.28 as the flame signal not being detected during the ignition phase, and F.29 as an unsuccessful re-ignition after a flame loss during operation. The codes describe when the flame went missing, not what removed it, and Vaillant lists insufficient gas, a blocked condensate pipe, and a faulty ignition electrode among the causes of both. Applies to: Vaillant ecoTEC gas boilers covered by the published United Kingdom fault code list These meanings come from Vaillant's own United Kingdom fault code list for its gas boilers and are written with a full stop between the letter and the number. Other manufacturers use F28 and F29 for entirely different conditions, and a code read from a non-Vaillant appliance does not carry these definitions. Owner-safe checks: Check whether other gas appliances in the property work and whether a prepayment meter has credit. | Look and listen for a gurgling or bubbling sound at the boiler or the external condensate pipe. | Thaw an accessible frozen condensate pipe with warm, not boiling, water poured along its length. | Reset the boiler once according to its own manual after the condensate pipe has drained. | Insulate the condensate pipe afterwards, as Vaillant recommends, to reduce the chance of a repeat. Qualified technician: The same code returning after one reset with the gas supply confirmed and the condensate pipe clear. | Any suspicion of an ignition electrode, gas valve, flue, or circuit board fault, all of which need the casing opened. | A condensate pipe that is not reachable from ground level. | F.54 shown alongside F.28 or F.29, which Vaillant attributes to the gas supply. | The smell of gas, which takes priority over every code on this page and is answered by evacuating and dialling 0800 111 999.

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F.23 ProfessionalRequired
Vaillant • boiler — Vaillant ecoTEC gas boilers covered by the Vaillant United Kingdom fault code list

Vaillant F.23: the temperature spread says water is barely moving

Vaillant defines F.23 as the temperature spread being too great, or water circulation too low. The boiler measures flow and return temperature and compares them, and when the difference grows beyond what the appliance allows, it concludes that not enough water is passing through the heat exchanger to carry the heat away. Applies to: Vaillant ecoTEC gas boilers covered by the Vaillant United Kingdom fault code list The definition used here is Vaillant's own fault code list for ecoTEC appliances sold in the United Kingdom. Vaillant uses different fault numbering on other ranges and in other markets, and a Glow-worm appliance, though part of the same group, has its own published list. Check the code against the label inside your own casing flap. Owner-safe checks: Feel each radiator after a heating attempt and note which get warm, which stay cold, and whether the cold ones are cold at the top or the bottom. | Check the pressure gauge and record the reading, since a system that has lost water often has air in its place. | Confirm that radiator valves and any thermostatic heads have not been closed off, particularly on circuits recently worked on. Qualified technician: Setting or replacing a pump, venting a sealed primary circuit, power flushing, and testing flow and return sensors are Gas Safe registered tasks on this appliance. | Kettling or banging from the boiler is a reason to stop using the heating rather than to keep trying, because boiling against the exchanger causes cumulative damage.

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F.22 ProfessionalRequired
Vaillant • boiler — Vaillant ecoTEC plus and ecoTEC sustain boilers that list F.22

Vaillant ecoTEC F.22 fault code: low water pressure explained

Vaillant assigns F.22 to low water pressure in the sealed heating circuit, and the boiler stops firing to protect itself from running dry. Vaillant names the normal range as 1 to 1.5 bar, and lists a faulty pressure sensor, loose sensor or pump wiring, and a failed internal expansion vessel alongside a genuine water shortage. Applies to: Vaillant ecoTEC plus and ecoTEC sustain boilers that list F.22 This meaning follows the Vaillant United Kingdom fault-code list for ecoTEC boilers that display F.22. Other Vaillant ranges and the same code on another appliance can be mapped differently, so confirm the model from the data badge before you top up or reset. Owner-safe checks: Read the pressure gauge with the system cold, and top up to about 1.5 bar with the filling loop only if it is below 1 bar, then close both valves fully. | Record how many times the pressure has needed topping up in the last month and whether it drops fastest hot or cold. Qualified technician: A repeated pressure loss, a suspected leak, an expansion vessel check, or any sensor or wiring inspection inside the boiler casing needs a Vaillant or Gas Safe registered engineer.

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Overflow switch trip ProfessionalRequired
Trane • air-handler — Trane air handlers and indoor coils fitted with a condensate overflow switch, as described in Trane homeowner support

Trane overflow switch shutdown: cooling stops and nothing looks broken

An overflow switch on a Trane air handler interrupts the cooling call when condensate rises past the level it watches. The outdoor unit stops, the thermostat still shows a call, and nothing inside the house looks wrong. That combination is the switch doing its job: it stops the system before water reaches the ceiling below. Applies to: Trane air handlers and indoor coils fitted with a condensate overflow switch, as described in Trane homeowner support Overflow switches are fitted in several positions, including the primary pan, the secondary pan, and in the drain line itself, and not every Trane installation has one. Which switch tripped and how it is wired depends on the installation rather than on the model, so the answer comes from the installer's arrangement as much as from Trane literature. Owner-safe checks: Confirm the thermostat is calling for cooling and that no breaker or fuse serving the indoor or outdoor unit has operated. | Look into any visible drain pan beneath the indoor unit and note whether it holds water or shows a waterline stain. | After the system has been asked to cool for a while, go and look at where the drain discharges outside and see whether anything came out. Qualified technician: Clearing a condensate drain line, testing an overflow switch, and correcting drain fall or trap arrangement are service tasks on this equipment. | Never bypass or unplug an overflow switch to restore cooling. It is the only thing standing between a blocked drain and water in the structure below.

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