What does the Vaillant ecoTEC pro F78 fault code mean?
The F78 fault code on the Vaillant ecoTEC pro indicates a problem with the system trends, which typically relates to the boiler’s ability to monitor and adapt to changes in heating demand. This can lead to inefficient operation and potential system failures if not addressed.
Common Causes
- Sensor Malfunction: A faulty temperature or pressure sensor may provide incorrect readings, causing the boiler to misinterpret system demands.
- Wiring Issues: Damaged or loose wiring connections can disrupt communication between components, leading to erroneous fault codes.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer to diagnose and repair the issue, as it involves electrical and gas components that require professional expertise for safety reasons.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for resolving an F78 fault could range around £150 to £250, primarily due to the need for professional diagnostics and potential replacement of sensors or wiring.