Vaillant Boiler Fault Codes
ecoTEC combi, system and heat-only boilers. Vaillant shows fault codes in an F.xx format on the display (for example F.22, F.28), each pointing to a specific fault the control board has detected.
Applies to: ecoTEC plus, ecoTEC pro, ecoFIT pure, ecoTEC exclusive
Vaillant F.20
Safety cut-out / overheat
The boiler has exceeded a safe temperature limit and shut down on its safety cut-out.
Vaillant F.22
Low water pressure / dry fire protection
The system water pressure is too low (or there is no water), so the boiler has shut down to protect itself.
Vaillant F.27
Flame simulation / residual flame detected
The boiler is detecting a flame signal when there should not be one, so it has shut down for safety.
Vaillant F.28
Ignition failure on startup
The boiler tried to light at startup but failed to establish a flame, so it has locked out for safety.
Vaillant F.29
Flame loss during operation
The boiler lit correctly but the flame went out while it was running, so it has locked out.
Vaillant F.62
Delayed gas valve shut-off (gas valve fault)
The gas valve is taking too long to shut off, so the boiler has flagged a gas valve fault.
Vaillant F.72
Flow / return temperature sensor fault
The boiler has detected an implausible difference between the flow and return temperature sensors.
Vaillant F.75
Pump / water pressure sensor fault
The boiler saw no pressure change when the pump started, pointing to a faulty pressure sensor, pump or expansion vessel.
On a boiler repair? Keep the job moving
TradePlanr turns the callout into paid work — log the job, quote the parts and labour, raise the gas safety record and send the invoice from your phone, even with no signal. Free to start, works in your browser, no download needed.
