What does the Vaillant ecoTEC exclusive F91 fault code mean?
The F91 fault code indicates a problem with data logging within the Vaillant ecoTEC exclusive boiler. This typically suggests that the boiler’s control system is unable to record or retrieve necessary operational data, which can affect performance.
Common Causes
- Faulty Control Board: The control board may be malfunctioning, preventing proper data logging.
- Wiring Issues: Damaged or loose wiring connections can disrupt communication between components, leading to logging failures.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer for this issue, as it involves electrical components and safety risks. Attempting to fix it yourself could lead to further damage or safety hazards.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for resolving the F91 fault could be around £250 to £400, primarily due to the potential need for a new control board and professional labour costs.