How much does it cost to fix Ideal error code 4 / C?

Typical repair cost for the Ideal 4 / C fault is £120-250 including labour.

4 / C High

Ideal 4 / C Fault Code

Q: What does the Ideal 4 / C fault code mean?

Your boiler has stopped working because it has either detected an overheating issue or an internal electrical safety fuse has failed.

Also written as 4C — same fault.

The Ideal 4 / C fault code means: your boiler has stopped working because it has either detected an overheating issue or an internal electrical safety fuse has failed.. It appears on 1 Ideal model in our database.

Technical description: Fuse F2 blown or temperature of burner thermostat too high or supply temperature too high.

Typical repair cost £120-250 (including labour)

Engineer required

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

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Ideal models that show the 4 / C fault code

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

Maximiser SE Repair: £120-250

Source

Ideal 4 / C fault code information on this page is sourced and cross-checked against the official Ideal service / installation manuals for each affected model.

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