What does the Baxi Duo-tec F78 fault code mean?
The F78 fault code on a Baxi Duo-tec boiler indicates a central heating timer fault, which typically means there is an issue with the timer or programmer that controls the heating schedule. This can prevent the boiler from operating as intended, affecting heating performance.
Common Causes
- Faulty Timer/Programmer: The timer or programmer may be malfunctioning, preventing it from sending the correct signals to the boiler.
- Wiring Issues: Damaged or loose wiring connections between the timer and the boiler can disrupt communication, leading to the fault code.
Can I fix it myself? (DIY)
If you are comfortable with basic electrical work, you can check the wiring connections for any visible damage or looseness. However, due to the potential risks associated with gas appliances, it is strongly recommended to call a Gas Safe Engineer for any repairs or replacements related to the timer or electrical components.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for a faulty timer or programmer on a Baxi Duo-tec boiler is approximately £150 to £250. This includes the cost of the replacement part and labour, as the timer is a critical component that requires professional installation to ensure safety and compliance with regulations.