What does the Worcester Bosch Greenstar CDi F27 fault code mean?
The F27 fault code indicates that the return temperature of the heating system is too high, which can prevent the boiler from operating efficiently. This issue may lead to overheating and potential damage if not addressed promptly.
Common Causes
- Blocked Heat Exchanger: A build-up of debris or scale can restrict water flow, causing the return temperature to rise.
- Faulty Thermistor: A malfunctioning thermistor may incorrectly read the temperature, leading to improper boiler operation.
Can I fix it myself? (DIY)
It is advisable to call a Gas Safe Engineer to diagnose and repair the issue, as it may involve gas or electrical components that require professional expertise.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for addressing the F27 fault could range from £150 to £300, depending on whether the issue is a blocked heat exchanger or a faulty thermistor that needs replacement.