F.040
The air ratio is too low.
Vaillant ecoTEC Plus Combi
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
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.
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
Fault in the electrical connection for the gas valve assembly
Measure
Check and, if required, replace the wiring harness for the gas valve assembly.
Possible cause
Gas valve assembly not electrically connected/incorrectly connected
Measure
Check the electrical connection to the gas valve assembly.
Possible cause
Control electrode defective
Measure
Check and, if required, replace the control electrode.
Possible cause
Burner defective
Measure
Check and, if required, replace the burner.
Possible cause
PCB defective
Measure
Replace the PCB.
Possible cause
Fan defective
Measure
Check and, if required, replace the fan.
Possible cause
Air-mass flow sensor dirty or defective (only in conjunction with the conversion set comprising the air intake pipe with integrated non-return valve and air-mass flow sensor)
Measure
1. Check the air-mass flow sensor for dirt.
2. If required, replace the entire air intake pipe.
Possible cause
Interruption in the wiring harness to the fan
Measure
Check the wiring harness between the PCB and fan, including all plug connections (especially on the PCB).
Possible cause
Using an incorrect wiring harness between the PCB and gas valve assembly
Measure
Check the article number of the wiring harness between the PCB and the gas valve assembly or heat cell, and replace the wiring harness if necessary.
This code also applies to: