How to fix Vaillant ecoTEC exclusive fault code F31

What does the Vaillant ecoTEC exclusive F31 fault code mean?

The F31 fault code indicates a malfunction with the flue gas temperature sensor in the Vaillant ecoTEC exclusive boiler. This sensor is crucial for monitoring the temperature of the flue gases to ensure safe and efficient operation.

Common Causes

  • Faulty Temperature Sensor: The sensor may be defective or damaged, leading to incorrect readings.
  • Wiring Issues: Damaged or loose wiring connections to the sensor can disrupt its functionality.

Can I fix it myself? (DIY)

It is strongly advised to call a Gas Safe Engineer for this issue, as it involves gas and electrical components that require professional expertise to ensure safety and compliance with regulations.

Estimated Repair Cost (2026 UK Prices)

The estimated repair cost for replacing the flue gas temperature sensor is around £150 to £200. This includes the cost of the part and labour, reflecting the complexity of the repair and the need for a qualified technician.