How much does it cost to fix Ideal error code 66 H.....1.....?

Typical repair cost for the Ideal 66 H.....1..... fault is £90-160 including labour.

66 H.....1..... High

Ideal 66 H.....1..... Fault Code

Q: What does the Ideal 66 H.....1..... fault code mean?

Your boiler has detected a problem with the sensor that monitors the temperature of the water leaving the unit, causing it to shut down as a safety precaution.

Also written as 66H1 — same fault.

The Ideal 66 H.....1..... fault code means: your boiler has detected a problem with the sensor that monitors the temperature of the water leaving the unit, causing it to shut down as a safety precaution.. It appears on 2 Ideal models in our database.

Technical description: FLOW THERMISTOR ERROR

Typical repair cost £90-160 (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 66 H.....1..... fault code

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

Source

Ideal 66 H.....1..... 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