What does the Heatline E04 fault code mean?

Your boiler is failing to light the internal burner, so it has safely shut itself down to prevent a gas build-up.

How much does it cost to fix Heatline error code E04?

Typical repair cost for the Heatline E04 fault is £120-250 including labour.

Manufacturer manual

Flame detection failure

Referenced from a related model

This code was carried over from a closely related model. Treat it as a guide and confirm against your boiler’s own manual.

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Lockout fault with a reset-needed pattern.

Older boilers — thermocouple, draught, gas supply.

7 signs repair isn't worth it anymore.