F.291
The flame has failed during the stabilisation period following flame loss during operation.
Vaillant ecoTEC Plus System
Possible cause
Gas flow pressure too low
Measure
Check the gas flow pressure and the external gas pressure switch.
Possible cause
Gas valve assembly offset incorrectly stored in D.052 and, if applicable, D.182
Measure
Check the offset setting for the gas valve assembly.
Possible cause
Incorrect gas type set
Measure
Check the gas type and the gas type setting under D.156 and D.157.
Possible cause
Gas valve assembly defective/incorrect spare part gas valve assembly
Measure
Check and, if required, replace the gas valve assembly.
Possible cause
Fault in the flue gas route caused by recirculation or flue gas blockage
Measure
Check the entire flue gas route.
Possible cause
Air intake pipe blocked
Measure
Check and, if required, replace the air intake pipe.
Possible cause
Ignition failed
Measure
1. Check the ignition using check programme P.021.
2. Product starts: Ignition electrode, ignition transformer, gas valve assembly and fan are working, gas is flowing and the gas volume is correct, no blockage or recirculation detected.
3. Product does not start and displays a fault code again: Carry out the next check for the cause.
Possible cause
Control electrode defective
Measure
Check and, if required, replace the control electrode.
Possible cause
Control electrode wiring harness defective
Measure
Check the wiring harness for the control electrode and, if required, replace it.
Possible cause
Condensate in the combustion chamber due to a blocked condensate discharge
Measure
1. Check and, if required, clean the condensate discharge pipe including the siphon.
2. Check that the condensate discharge has been installed correctly.
3. Check the combustion chamber (electrodes, insulating mats, burner).
4. If required, replace the insulating mats in the combustion chamber.
Possible cause
Condensate pump (if fitted) defective
Measure
Check and clean the condensate pump. Replace the condensate pump, if required.
This code also applies to: