What does the Ideal Mexico HE F91 fault code mean?
The F91 fault code on the Ideal Mexico HE boiler indicates a Domestic Hot Water (DHW) update fault, which typically suggests an issue with the boiler’s ability to heat water effectively. This can lead to inadequate hot water supply or inconsistent temperature control.
Common Causes
- Faulty DHW Sensor: A malfunctioning sensor may fail to accurately detect water temperature, causing the boiler to mismanage heating cycles.
- Blocked Heat Exchanger: A blockage in the heat exchanger can restrict water flow, preventing efficient heating and triggering the fault code.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer for this issue, as it involves gas and electrical components that require professional handling. Attempting DIY repairs could pose safety risks.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for resolving the F91 fault could range from £150 to £300, depending on whether the DHW sensor or heat exchanger needs replacement. This estimate includes parts and labour, reflecting the complexity of the repair.