Fan does not run High

Glow-worm Fan does not run Fault Code

Also written as FANDOESNOTRUN — same fault.

The Glow-worm Fan does not run fault code means: your boiler has stopped working because the internal fan, which safely exhausts fumes, isn't starting up.. It appears on 2 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: Check if there is 230V~ between motor connections on fan. If yes, replace fan. If no, isolate electrical supply test fan harness continuity; if satisfactory replace printed circuit board.

What causes the Glow-worm Fan does not run fault?

This fault occurs when the boiler's control system attempts to start the fan but detects no movement or electrical response. The most common reasons are a seized fan motor due to age-related wear or a failure on the main circuit board which prevents power from reaching the motor.

This issue is more frequent in autumn when boilers are turned back on after a summer of inactivity, as the fan motor can seize up during long periods of disuse.

Typical repair cost £250-£480 (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 Fan does not run fault code

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

Source

Glow-worm Fan does not run 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