BoilerFaultCodes.com
L5 High Lockout

Your boiler has been manually reset too many times in a short window of time as it tries to clear a persistent underlying 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 boiler resets in 15 minutes

What causes this fault?

This fault occurs when the boiler is manually reset five times within a fifteen-minute window, causing the system to lock you out for safety. It is usually triggered because you are trying to clear a different, persistent error that hasn't been fixed, such as an ignition or flame failure. The boiler essentially stops responding to prevent potential damage from repeated failed start-up attempts.

Typical repair cost £0-120 (including labour)

DIY fix possible

Turn the power supply 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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Protect yourself from future repair bills

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