High Lockout
18 on Glow-worm Ci Plus

Your boiler's main control panel has lost communication with the internal system, meaning your settings or commands aren't being processed correctly.

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

Local user interface fault

What causes this fault?

This fault occurs when the digital connection between the boiler's display screen and the main internal brain is broken. The most common reason is a loose or damaged wiring connection between the two components, though it can also be caused by an electrical failure on one of the circuit boards themselves.

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 guides you might find useful

Boiler keeps cutting out

Lockout fault with a reset-needed pattern.

Read →

Yellow or orange flame — CO safety

Safety-critical — turn off, read this.

Read →

When to replace your boiler

7 signs repair isn't worth it anymore.

Read →