What does the Vaillant ecoTEC pro F55 fault code mean?
The F55 fault code on a Vaillant ecoTEC pro boiler indicates a problem with the hot water demand, often related to the flow sensor or the control board. This issue prevents the boiler from properly detecting when hot water is required, leading to a lack of hot water supply.
Common Causes
- Faulty Flow Sensor: The flow sensor may be malfunctioning, causing incorrect readings and preventing the boiler from activating the hot water function.
- Control Board Issues: A fault in the control board can disrupt communication between components, leading to failure in responding to hot water demands.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer for this issue, as it involves gas and electrical components that require professional expertise. Attempting DIY repairs could be dangerous and may void your warranty.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for resolving the F55 fault could range from £150 to £300, depending on whether the flow sensor or control board needs replacement. This estimate includes parts and labour, reflecting the complexity of diagnosing and fixing electronic components.