High Lockout
e6 on Remeha Avanta 18V

Your boiler detects a flame when it isn't supposed to be running, which is a safety conflict that prevents it from starting up.

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

Unwanted flame formation

What causes this fault?

This fault occurs when the boiler's internal sensor detects a flame signal at a time when the unit should be switched off. The most common reasons are a damaged sensor electrode sending a false signal or a faulty gas valve that is failing to close fully, allowing a tiny amount of gas to leak and burn.

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

e4View →e36View →

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 →