What does the Baxi Duo-tec F45 fault code mean?
The F45 fault code on a Baxi Duo-tec boiler indicates a fault with the domestic hot water (DHW) thermistor. This component is responsible for measuring the temperature of the water, and a malfunction can lead to issues with hot water delivery.
Common Causes
- Faulty DHW Thermistor: The thermistor may be defective or damaged, leading to incorrect temperature readings.
- Wiring Issues: Damaged or loose wiring connections to the thermistor can cause communication failures between the thermistor and the boiler control board.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer for this issue, as it involves electrical components and gas safety regulations. Attempting to fix it yourself could pose safety risks.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for replacing a DHW thermistor on a Baxi Duo-tec boiler is around £120. 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.