High
Lockout light illuminated on Potterton Promax HE

Your boiler has switched itself off for safety reasons because it cannot light its flame or has become too hot to operate.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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.

What the manual says

Manufacturer manual

Loss of gas supply, flame failure, or over-heating of the central heating water will cause the appliance to shut down or Lockout.

From this model's manual
Verified against the Potterton Boiler Puma installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

E119View →E133View →E168View →

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