High Lockout
L8 on Ideal Logic Max Combi

Your boiler's main internal computer has lost its settings or has developed an internal electrical fault, preventing it from starting.

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

PCB UNCONFIGURED OR FAULTY

What causes this fault?

This fault occurs when the boiler's main control board loses the essential software instructions needed to operate the system safely. The most common reason is a memory failure within the data chip or an electrical surge that has corrupted the board's internal settings, meaning the boiler no longer knows which model it is or how to fire correctly.

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

F7View →L2View →F1View →L1View →

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 →