E12 High

Heatline E12 Fault Code

The Heatline E12 fault code means: your boiler's internal computer brain has suffered a software memory failure and can no longer process instructions.. It appears on 2 Heatline models in our database.

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: Internal PCB error (EEPROM memory error)
Typical repair cost £280-450 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →

Heatline models that show the E12 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Heatline E12 fault code information on this page is sourced and cross-checked against the official Heatline service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026