What does the Vaillant ecoTEC pro F91 fault code mean?
The F91 fault code on the Vaillant ecoTEC pro indicates a problem with the system configurations, which may affect the boiler’s ability to operate correctly. This can arise from incorrect settings or issues with the boiler’s internal components.
Common Causes
- Incorrect System Configuration: The boiler may have been set up incorrectly during installation or maintenance, leading to communication issues.
- Faulty Wiring or Connections: Damaged or loose wiring can disrupt the signals between components, causing the fault code to appear.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer for this issue, as it involves complex system configurations and potential safety risks. Attempting to fix it without proper expertise may lead to further complications.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for resolving the F91 fault code is around £150 to £250. This includes diagnostics and potential reconfiguration of the system, which requires professional expertise.