F.077
A condensate pump or an external flue non-return flap is blocking the burner operation.
Vaillant ecoTEC Plus Combi
Possible cause
Interruption in the wiring harness
Measure
Check the wiring harness including all plug connections and, if required, replace it (PCB plug X20, contact 3/14).
Possible cause
No feedback from the flue non-return flap or the feedback is incorrect
Measure
Check that the flue non-return flap functions correctly.
Possible cause
Flue non-return flap defective
Measure
Replace the flue non-return flap.
Possible cause
Fault in the electrical connection to the condensate pump
Measure
Check the electrical connection to the condensate pump.
Possible cause
Condensate pump defective
Measure
Replace the condensate pump.