What does the Worcester Bosch Greenstar i F77 fault code mean?
The F77 fault code indicates a reliability issue within the system, often related to the boiler’s internal components or communication errors. This can lead to the boiler shutting down to prevent further damage or unsafe operation.
Common Causes
- Faulty PCB: A malfunctioning printed circuit board can disrupt communication between components, triggering the F77 error.
- Sensor Issues: Defective temperature or pressure sensors may provide incorrect readings, causing the system to fail its reliability checks.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer for this issue, as it may involve complex electrical components and safety risks. Attempting DIY repairs could void your warranty or lead to unsafe conditions.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for resolving the F77 fault could range from £150 to £300, depending on whether the PCB needs replacing or if sensors require recalibration. This cost reflects the complexity of the components involved and the expertise required for safe repairs.