How much does it cost to fix Ideal error code 86 H.....3.....?

Typical repair cost for the Ideal 86 H.....3..... fault is £120-200 including labour.

86 H.....3..... Medium

Ideal 86 H.....3..... Fault Code

Q: What does the Ideal 86 H.....3..... fault code mean?

Your boiler is struggling to accurately measure the temperature of your hot water, which may cause your taps to run cold or the water temperature to fluctuate.

Also written as 86H3 — same fault.

The Ideal 86 H.....3..... fault code means: your boiler is struggling to accurately measure the temperature of your hot water, which may cause your taps to run cold or the water temperature to fluctuate.. It appears on 2 Ideal models in our database.

Technical description: DHW THERMISTOR ERROR

Typical repair cost £120-200 (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 86 H.....3..... fault code

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

Source

Ideal 86 H.....3..... 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