F12 - Domestic Hot Water (DHW) outlet sensor short circuit

What does F12 mean?

The Vaillant Ecotec Plus Boilers have detected a short circuit in the sensor that monitors the temperature of the outgoing domestic hot water (DHW). This electrical fault often occurs in conjunction with fault F.91.

• Defective NTC sensor.
• Short circuit in the cable harness.
• Damaged cable or sensor casing.

Click steps to track your progress.

1. 1

   Check the NTC sensor connection to ensure it is properly attached and secure.

2. 2

   Inspect the cable harness for any signs of damage, wear, or loose wiring.

3. 3

   If you are able, check the NTC resistance and harness continuity using appropriate tools.

4. 4

   If the problem continues, it is recommended to seek assistance from a professional heating technician.