How to fix Worcester Bosch Greenstar Si fault code F85

What does the Worcester Bosch Greenstar Si F85 fault code mean?

The F85 fault code on the Worcester Bosch Greenstar Si indicates a problem related to system maintenance, typically suggesting that the boiler requires attention due to issues such as low water pressure or a fault in the heating system. This code serves as a warning for users to check the system’s operational status and perform necessary maintenance.

Common Causes

  • Low Water Pressure: Insufficient water pressure in the system can trigger the F85 fault code, indicating that the boiler cannot operate effectively.
  • Blocked Filters or Pipes: Blockages in the heating system can prevent proper water flow, leading to maintenance issues and the activation of the fault code.

Can I fix it myself? (DIY)

It is advisable to check the boiler’s pressure gauge and ensure it is within the recommended range (typically 1-1.5 bar). If the pressure is low, you can carefully top it up using the filling loop. However, for any gas or electrical issues, it is crucial to call a qualified Gas Safe Engineer.

Estimated Repair Cost (2026 UK Prices)

The estimated repair cost for addressing the F85 fault code is around £150-£250, primarily for servicing and potential replacement of blocked components. This cost reflects the need for professional intervention to ensure safe and effective repairs.