What does the Vaillant ecoTEC plus F90 fault code mean?
The F90 fault code on a Vaillant ecoTEC plus indicates a problem with the system resources, which may affect the boiler’s ability to operate efficiently. This could be due to issues such as low water pressure or a fault in the electronic control system.
Common Causes
- Low Water Pressure: Insufficient water pressure can prevent the boiler from functioning properly, triggering the F90 error.
- Faulty Electronic Control: A malfunction in the boiler’s electronic components can lead to incorrect readings and the F90 fault code being displayed.
Can I fix it myself? (DIY)
If you are comfortable with basic maintenance, check the water pressure and ensure it is within the recommended range (typically 1-1.5 bar). If the pressure is low, you can top it up using the filling loop. However, for any electrical issues or if the fault persists, it is essential to call a Gas Safe Engineer.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for resolving the F90 fault could range from £150 to £300, depending on whether it requires a simple pressure adjustment or a more complex electronic component replacement.