F.011
The return temperature sensor has short-circuited.
Vaillant ecoTEC Plus System
Possible cause
Fault in the electrical connection for the return temperature sensor
Measure
Check and, if required, replace the wiring harness between the PCB and sensor, including all plug connections.
Possible cause
Return temperature sensor defective
Measure
Check and, if required, replace the return temperature sensor.
This code also applies to: