What does the Glow-worm Ultimate F96 fault code mean?
The F96 fault code indicates a problem with the domestic hot water (DHW) thermistor, which is responsible for measuring the temperature of the water. This warning suggests that the thermistor may be faulty or there is an issue with the wiring or connections related to it.
Common Causes
- Faulty DHW Thermistor: The thermistor itself may be defective, leading to incorrect temperature readings.
- Wiring Issues: Damaged or loose wiring connections to the thermistor can cause communication failures between the thermistor and the boiler’s control board.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer to diagnose and repair this issue, as it involves electrical components and gas safety regulations. Attempting to fix it yourself could be dangerous.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for replacing the DHW thermistor is around £120, which includes the part and labour. This is based on typical service rates and the cost of the thermistor itself.