What does the Ideal Mexico HE F42 fault code mean?
The F42 fault code on the Ideal Mexico HE boiler indicates a domestic hot water (DHW) temperature fault. This typically means that the boiler is unable to maintain the desired temperature for the hot water supply.
Common Causes
- Faulty DHW Sensor: The temperature sensor may be malfunctioning, leading to incorrect readings and triggering the fault code.
- Blocked Heat Exchanger: A blockage in the heat exchanger can prevent proper heat transfer, affecting the hot water temperature.
Can I fix it myself? (DIY)
It is advisable to call a Gas Safe Engineer for this issue, as it involves gas and electrical components that require professional handling for safety and compliance.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for resolving the F42 fault could be around £150 to £250, primarily depending on whether the DHW sensor needs replacement or if the heat exchanger requires cleaning or servicing.