F.72
Vaillant
Flow and Return Temperature Sensor Difference Implausible
F.72 flow/return sensor mismatch; appliance may not modulate correctly
Advertisements
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Advertisements
Possible Causes
Flow and return NTCs swapped, One NTC faulty, Poor contact of one sensor, Wiring harness crossed
How to Fix / Troubleshooting
Safety: Isolate power and gas.
- Verify sensor positions: Confirm that the flow NTC is on the outlet and the return NTC on the inlet/return as per Vaillant diagrams. Correct any swapped sensors.
- Check wiring: Ensure the NTC leads are connected to the correct PCB terminals and not crossed.
- Test both NTCs: Measure resistance of both sensors at the same temperature; values should be similar. Replace any sensor that is out of tolerance.
- Reset and test: After corrections, reset the fault and observe operation under load.
Advertisements
Repair Difficulty
Medium
3/5
Required Part
Flow and Return NTC Sensors
Check Price on Amazon
We may earn a commission from links on this page.
Advertisements