How to fix Worcester Bosch Greenstar i fault code F84

What does the Worcester Bosch Greenstar i F84 fault code mean?

The F84 fault code indicates a problem with the system support, which may affect the boiler’s ability to operate efficiently. This could be due to issues with the system pressure or a malfunction in the control circuitry.

Common Causes

  • Low System Pressure: Insufficient water pressure in the heating system can trigger the F84 fault code.
  • Faulty Sensors or Wiring: Malfunctioning sensors or damaged wiring can lead to incorrect readings, causing the boiler to display the F84 error.

Can I fix it myself? (DIY)

If you are comfortable, check the system pressure and ensure it is within the recommended range (usually 1-1.5 bar). 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 Gas Safe Engineer.

Estimated Repair Cost (2026 UK Prices)

The estimated repair cost for addressing the F84 fault could range from £100 to £250, depending on whether it requires a simple pressure adjustment or more complex repairs involving sensor replacement or wiring issues.