What does the Baxi Duo-tec F89 fault code mean?
The F89 fault code on the Baxi Duo-tec indicates a Domestic Hot Water (DHW) service fault, which typically means there is an issue with the boiler’s ability to heat water for taps and showers. This can be due to various factors affecting the hot water system.
Common Causes
- Blocked Heat Exchanger: A build-up of limescale or debris can restrict water flow and heat transfer.
- Faulty DHW Sensor: If the sensor that monitors water temperature is malfunctioning, it may prevent the boiler from operating correctly.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer for this issue, as it may involve gas or electrical components that require professional expertise. Attempting DIY repairs could be dangerous.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for resolving an F89 fault could range from £150 to £300, depending on whether the heat exchanger needs cleaning or the DHW sensor needs replacement. This estimate includes parts and labour.