What does the Baxi Duo-tec F34 fault code mean?
The F34 fault code on a Baxi Duo-tec boiler indicates a thermistor fault, which typically means that the temperature sensor is malfunctioning or has failed. This can lead to incorrect temperature readings and affect the boiler’s performance.
Common Causes
- Faulty Thermistor: The thermistor may be damaged or have an internal fault, causing it to provide inaccurate readings.
- Wiring Issues: Damaged or loose wiring connections to the thermistor can lead to communication failures between the sensor and the boiler’s control board.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer to diagnose and repair the thermistor fault, as working with gas appliances can be dangerous. Attempting to fix electrical components without proper training can also pose safety risks.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for a thermistor replacement on a Baxi Duo-tec boiler is around £120-£150. This includes the cost of the part and labour, as the thermistor itself is relatively inexpensive, but professional installation is necessary for safety and compliance.