High Lockout
E83468 on Potterton Powermax HE

Your boiler has detected a problem with the internal sensor that monitors the flame, meaning it cannot confirm it is burning fuel safely and has stopped working.

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

Electrode/Ionization Kit Incl.key no’s 8 & 9

What causes this fault?

This fault occurs when the boiler's internal computer can no longer detect a steady flame during the ignition process. The most common reason is that the detection probes have become carbonised or worn out over time, preventing them from sending the necessary electrical signal to confirm it is safe to keep the gas on.

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

E01View →E02View →

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 →