High
Lockout light illuminated on Potterton Puma 100e

Your boiler has stopped working for safety reasons because it either cannot light the flame or the system has become too hot.

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.

Technical description

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

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.

Find a Gas Safe engineer
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