What does the Worcester Bosch Greenstar Si F78 fault code mean?
The F78 fault code indicates a problem with the system flow, which can prevent the boiler from operating efficiently. This issue often relates to insufficient water flow through the heating system, affecting the boiler’s ability to heat effectively.
Common Causes
- Blocked Filter: A blockage in the system filter can restrict water flow, leading to the F78 fault code.
- Pump Failure: If the circulation pump is malfunctioning or has failed, it may not be able to move water through the system properly.
Can I fix it myself? (DIY)
It is advisable to call a Gas Safe Engineer for this issue, as it may involve gas or electrical components that require professional handling. Attempting to fix it yourself could pose safety risks.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for addressing the F78 fault could be around £150 to £250, depending on whether a filter cleaning or pump replacement is needed. This cost reflects the complexity of diagnosing and resolving flow issues in the system.