How much does it cost to fix Heatline error code E35?

Typical repair cost for the Heatline E35 fault is £120-£280 including labour.

E35 High

Heatline E35 Fault Code

Q: What does the Heatline E35 fault code mean?

Your boiler thinks it sees a flame even though the gas should be turned off, which is a safety conflict that prevents the system from starting.

The Heatline E35 fault code means: your boiler thinks it sees a flame even though the gas should be turned off, which is a safety conflict that prevents the system from starting.. It appears on 2 Heatline models in our database.

Technical description: Flame sensing fault: A flame is detected when the gas valve is supposed to be closed.

Typical repair cost £120-£280 (including labour)

Engineer required

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

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Heatline models that show the E35 fault code

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

Source

Heatline E35 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