Vaillant aroTHERM fault F.073

What it means

Fault with the building circuit water pressure sensor.

Likely causes

1. The sensor is not connected or the sensor input has short-circuited
2. Heating water leak
3. Loss of system pressure
4. Low or high system filling pressure
5. Leak in heating circuit
6. Air in system
7. Filling pressure outside permitted range causes flashing indication
8. Loss of heating water
9. Pressure drop below minimum threshold
10. Pressure drop in system

Where to start

1. Check the sensor
2. Check building circuit pressure via Menu → Live Monitor → Building circuit pressure
3. Observe filling pressure symbol on control panel display