What does the Viessmann Vitodens 111-W F42 fault code mean?
The F42 fault code indicates a malfunction with the return temperature sensor in the Viessmann Vitodens 111-W boiler. This sensor is crucial for monitoring the temperature of the water returning from the heating system, and its failure can disrupt the boiler’s operation.
Common Causes
- Faulty Sensor: The return temperature sensor may be defective or damaged, leading to inaccurate readings.
- Wiring Issues: Damaged or loose wiring connections to the sensor can cause communication failures between the sensor and the boiler control unit.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer to diagnose and repair this issue, as it involves electrical components and safety risks associated with gas appliances.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for replacing the return temperature sensor is around £150 to £200, which includes parts and labour. This cost reflects the typical price for sensor replacement and the expertise required for safe installation.