F.11 — Return NTC short circuit

What does F.11 mean?

The return temperature sensor circuit has a short circuit. This prevents the boiler from accurately reading the return temperature, which can lead to incorrect operation.

• Return NTC sensor is defective.
• Short circuit within the cable harness connected to the sensor.
• Damage to the cable or casing causing a short.

Click steps to track your progress.

1. 1

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

2. 2

   Carefully inspect visible cables around the return sensor for any signs of damage or pinching.

3. 3

   If the fault persists after checking and resetting, contact Vaillant Service Solutions to inspect the sensor and wiring.