BoilerFaultCodes.com
L 0C High Lockout

Your boiler is repeatedly shutting down and trying to restart itself, likely due to an underlying component failure preventing reliable ignition.

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: Restart occurs 5 times within 15 minutes.

What causes this fault?

This fault occurs when the boiler senses a repeated failure to maintain a steady flame, causing it to shut down and attempt to restart itself five times in a short period. The most common reason is that the internal sensors or gas components are struggling to confirm a safe ignition, eventually leading the system to lock itself out for safety.

Typical repair cost £120-£350 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Find a Gas Safe engineer

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Protect yourself from future repair bills

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