How to fix Worcester Bosch Greenstar Si fault code F39

What does the Worcester Bosch Greenstar Si F39 fault code mean?

The F39 fault code indicates a problem with the system pressure sensor in the Worcester Bosch Greenstar Si boiler. This sensor is crucial for monitoring the water pressure within the system, and a fault can lead to improper operation or safety issues.

Common Causes

  • Faulty Pressure Sensor: The sensor itself may be defective or malfunctioning, leading to incorrect pressure readings.
  • Wiring Issues: Damaged or loose wiring connections to the pressure sensor can disrupt its functionality and cause the fault code to appear.

Can I fix it myself? (DIY)

It is recommended to call a Gas Safe Engineer to diagnose and repair the issue, as working with gas appliances can be dangerous. Attempting to fix electrical or gas-related issues without proper training can lead to serious safety risks.

Estimated Repair Cost (2026 UK Prices)

The estimated repair cost for replacing a faulty pressure sensor in a Worcester Bosch Greenstar Si boiler is approximately £150 to £200. This cost includes the price of the part and labour, reflecting the complexity of the repair and the need for a qualified technician.