What does the Worcester Bosch Greenstar Si F90 fault code mean?
The F90 fault code indicates a calibration issue within the heating system of the Worcester Bosch Greenstar Si boiler. This typically means that the boiler is unable to accurately measure or control the system pressure or temperature, leading to operational inefficiencies.
Common Causes
- Incorrect Pressure Settings: If the system pressure is too low or too high, it can lead to calibration errors.
- Faulty Sensors: Malfunctioning temperature or pressure sensors can provide inaccurate readings, causing the boiler to miscalculate system parameters.
Can I fix it myself? (DIY)
It is advisable to check the system pressure and ensure it is within the manufacturer’s recommended range. If the pressure is low, you can top it up using the filling loop. However, for any electrical or gas-related issues, it is crucial to call a qualified Gas Safe Engineer.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for addressing the F90 fault could range around £150 to £250, primarily depending on whether sensor replacements are needed or if recalibration is required. This cost reflects the typical service call and parts replacement for sensor issues.