F.317
The signal for the volume flow sensor in the domestic hot water circuit is implausible.
Vaillant ecoTEC Plus Combi
Possible cause
Fault in the electrical connection for the volume flow sensor in the domestic hot water circuit
Measure
Check the wiring harness between the PCB and volume flow sensor, including all plug connections.
Possible cause
Volume flow sensor in the domestic hot water circuit defective
Measure
Replace the volume flow sensor in the domestic hot water circuit.