How much does it cost to fix Ideal error code 1 / C?

Typical repair cost for the Ideal 1 / C fault is £120-250 including labour.

1 / C High

Ideal 1 / C Fault Code

Q: What does the Ideal 1 / C fault code mean?

Your boiler has detected a loose or faulty safety connection near the flue, which is preventing it from firing up reliably.

Also written as 1C — same fault.

The Ideal 1 / C fault code means: your boiler has detected a loose or faulty safety connection near the flue, which is preventing it from firing up reliably.. It appears on 1 Ideal model in our database.

Technical description: Connection for flue gas thermostat not closed.

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 1 / C fault code

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

Maximiser SE Repair: £120-250

Source

Ideal 1 / 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