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

What Does Error F.28 Mean?

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.