F.10 High

Glow-worm F.10 Fault Code

Also written as F10 — same fault.

The Glow-worm F.10 fault code means: your boiler has detected an electrical fault with the internal sensor that monitors the temperature of the water leaving the unit, causing it to shut down for safety.. It appears on 6 Glow-worm models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Flow temperature sensor short circuit

What causes the Glow-worm F.10 fault?

This fault occurs when the electrical connection to the flow sensor is compromised, usually due to an internal short circuit or water damage. The most common reason is that the sensor's internal insulation has failed, or moisture has seeped into the terminal, causing it to send an incorrect electrical signal to the main control board.

Typical repair cost £90-160 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Glow-worm models that show the F.10 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Glow-worm F.10 fault code information on this page is sourced and cross-checked against the official Glow-worm service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026