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

Typical repair cost for the Heatline E04 fault is £0-120 including labour.

E04 High

Heatline E04 Fault Code

Q: What does the Heatline E04 fault code mean?

Your boiler has stopped working because the water pressure is too low, usually because the system needs top-up or there is a small leak.

The Heatline E04 fault code means: your boiler has stopped working because the water pressure is too low, usually because the system needs top-up or there is a small leak.. It appears on 4 Heatline models in our database.

Technical description: Water pressure low: The system water pressure has dropped below the minimum operating level (typically 0.5 bar).

Typical repair cost £0-120 (including labour)

DIY fix possible

Locate the filling loop (usually a silver flexible hose) underneath the boiler.Slowly open the valve or valves on the filling loop until you hear water entering the system.Watch the pressure gauge until it reaches between 1.0 and 1.5 bar, then close the valves tightly.

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Heatline models that show the E04 fault code

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

Source

Heatline E04 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