BoilerFaultCodes.com
L5 High Lockout

Your boiler has stopped working because it has been reset too many times in a short period, likely triggered by an underlying recurring fault.

Call an engineer soon

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

Technical description: 5 x Boiler Resets in 15 mins

What causes this fault?

This fault occurs when the boiler's safety system detects that it has been reset five times within a fifteen-minute window. It is a protective 'lockout' designed to prevent further damage or safety risks while an underlying, unresolved issue keeps causing the boiler to fail. The root cause is typically a recurring ignition problem or a failing component that is preventing the boiler from firing up correctly.

Typical repair cost £100-350 (including labour)

DIY fix possible

Turn the power to the boiler off at the fused spur switchWait for 30 secondsTurn the power back on to clear the lockout memory

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