BoilerFaultCodesPotterton FAN LOCKOUT Fault Code
Also written as FANLOCKOUT — same fault.
The Potterton FAN LOCKOUT fault code means: your boiler's fan, which safely clears exhaust gases from the unit, has stopped spinning correctly and prevented the system from firing up.. It appears on 2 Potterton models in our database.
Technical description: Lights: On * * Off. Possible causes: Fan wiring continuity fault, fan PCB connection failure, or fan failure.
What causes the Potterton FAN LOCKOUT fault?
This fault occurs when the boiler's control board tries to start the fan but doesn't receive the correct signal that it is spinning at the right speed. The most common reasons are a build-up of debris causing the fan to seize or an electrical failure within the fan's motor or the main circuit board. Without the fan running correctly, the boiler cannot safely remove exhaust gases, so it shut downs for safety.
This fault is more common in winter, as the fan has to work much harder and for longer periods during cold spells, which can cause older motors to fail.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Potterton models that show the FAN LOCKOUT fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton FAN LOCKOUT fault code information on this page is sourced and cross-checked against the official Potterton service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026