High Lockout
L 0C on Ideal Logic Max Combi

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

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

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.

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
Search the official register →

Related fault codes

L2View →F2View →L1View →

Related guides you might find useful

Boiler keeps cutting out

Lockout fault with a reset-needed pattern.

Read →

Pilot light keeps going out

Older boilers — thermocouple, draught, gas supply.

Read →

Yellow or orange flame — CO safety

Safety-critical — turn off, read this.

Read →