How to fix Glow-worm Ultimate fault code F56

What does the Glow-worm Ultimate F56 fault code mean?

The F56 fault code indicates a domestic hot water (DHW) pressure failure in the Glow-worm Ultimate boiler. This typically means that the system is unable to maintain the required pressure for hot water delivery, which can affect performance.

Common Causes

  • Low Water Pressure: Insufficient water pressure in the system can lead to this fault, often due to leaks or insufficient filling.
  • Faulty Pressure Sensor: A malfunctioning pressure sensor may incorrectly report pressure levels, triggering the F56 fault code.

Can I fix it myself? (DIY)

If you are comfortable, you can check the boiler’s pressure gauge and top up the system pressure if it is low (typically below 1 bar). However, if the issue persists or involves gas or electrical components, it is crucial to call a Gas Safe Engineer.

Estimated Repair Cost (2026 UK Prices)

The estimated repair cost for addressing the F56 fault could be around £150 to £250, primarily for replacing a faulty pressure sensor or repairing leaks, depending on the specific issue identified during diagnosis.