High Lockout
PCB Fault on Ideal Logic Max Heat

Your boiler's internal computer has suffered a critical failure and can no longer control the heating system safely.

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

Contact Installer

What causes this fault?

This fault occurs when the boiler's main control board suffers an electrical failure, preventing it from processing instructions or monitoring safety sensors. The most common reasons are internal component wear, moisture ingress, or an electrical surge that has damaged the delicate circuitry on the board.

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 →