What does the Ideal Mexico HE F66 fault code mean?
The F66 fault code on the Ideal Mexico HE indicates a fault with the central heating (CH) thermistor, which is responsible for measuring the temperature of the water in the heating system. This fault can lead to improper heating performance or system shutdown.
Common Causes
- Faulty Thermistor: The thermistor may be defective or damaged, causing incorrect temperature readings.
- Wiring Issues: There could be a problem with the wiring connections to the thermistor, such as corrosion or disconnection.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer to diagnose and repair this issue, as it involves gas and electrical components that can be dangerous if handled improperly.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for replacing the CH thermistor on an Ideal Mexico HE is approximately £120. This includes the cost of the part and labour, as thermistor replacements typically require professional installation.