F.74 — Water pressure sensor signal too high

What does F.74 mean?

The water pressure sensor is sending a signal that is outside the correct range and too high. This can be due to wiring issues or a faulty sensor.

• Cable to the water pressure sensor has short-circuited at 5 V/24 V.
• Internal fault within the water pressure sensor itself.

Click steps to track your progress.

1. 1

   Press the fault clearance key on the boiler to reset it.

2. 2

   Visually inspect any accessible wiring connected to the water pressure sensor for damage or incorrect connections.

3. 3

   If the fault persists, contact Vaillant Service Solutions, as this indicates a sensor or electrical wiring problem.