F.025
The flue gas temperature is too high.
Vaillant ecoTEC Plus System
Possible cause
Wiring harness defective
Measure
Check the wiring harness including all plug connections and, if required, replace it (PCB plug X20, contact 14/15).
Possible cause
If present: Flue gas temperature monitor has triggered
Measure
Check and, if required, replace the flue gas temperature monitor.
This code also applies to: