F.343
The signal for the air-mass flow sensor is not plausible.
Vaillant ecoTEC Plus Combi
Possible cause
Air-mass flow sensor plug loose/not plugged in
Measure
Check the plug and the plug connection for the air-mass flow sensor.
Possible cause
Plug on PCB loose/not plugged in
Measure
Check the plug and the plug connection.
Possible cause
Interruption in the wiring harness
Measure
Check the wiring harness including all plug connections and, if required, replace it.
Possible cause
Measurement discrepancy too high. Air-mass flow sensor dirty.
Measure
Check the air-mass flow sensor for dirt.
Possible cause
You exit the measuring range permanently. Air-mass flow sensor defective
Measure
Replace the entire air intake pipe.
Possible cause
PCB defective
Measure
Replace the PCB.