F.028
The flame signal was not detected during the ignition phase.
Vaillant ecoTEC Plus Combi
Possible cause
Hard ignition takes place
Measure
1. Check the heat exchanger, siphon, siphon adapter, siphon hose (connection between the primary heat exchanger and the siphon, and siphon hose outside of the product), flue pipe adapter, unit housing, front casing and side section for possible damage.
2. If required, replace any damaged parts immediately.
Possible cause
Gas isolator cock closed
Measure
Open the gas isolator cock.
Possible cause
Gas connection pressure too low
Measure
Check the gas connection pressure.
Possible cause
Air in the gas supply (e.g. during initial start-up)
Measure
Reset the unit once.
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 offset incorrectly stored in D.052 and, if applicable, D.182
Measure
Check the offset setting for the gas valve assembly.
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
Gas flow pressure too low
Measure
Check the gas flow pressure and the external gas pressure switch.
Possible cause
Control electrode comes into contact with the burner
Measure
1. Check the clearance between the control electrode and the burner.
2. Check and, if required, replace the control electrode.
Possible cause
Ignition electrode defective
Measure
Check and, if required, replace the ignition electrode.
Possible cause
Ignition failed (for liquefied petroleum gas only)
Measure
Run check programme P.022.
Possible cause
Burner defective
Measure
Check and, if required, replace the burner.
Possible cause
Gas valve assembly defective/incorrect spare part gas valve assembly
Measure
Check and, if required, replace the gas valve assembly.
Possible cause
Interruption in the wiring harness
Measure
Check the wiring harness including all plug connections and, if required, replace it.
Possible cause
Earthing defective
Measure
Check the product's earthing.
Possible cause
Ionisation flow interrupted
Measure
Check the control electrode, the connection cable and the plug connection.
Possible cause
Fault in the flue gas route caused by recirculation or flue gas blockage
Measure
Check the entire flue gas route.
Possible cause
Ignition transformer not connected
Measure
Check the plug and the plug connection.
Possible cause
Defective ignition transformer
Measure
Check that the ignition transformer is working correctly and, if required, replace it.
Possible cause
PCB defective
Measure
Replace the PCB.
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.