How much does it cost to fix Ideal error code 90 H......n........?

Typical repair cost for the Ideal 90 H......n........ fault is £100-200 including labour.

90 H......n........ High

Ideal 90 H......n........ Fault Code

Q: What does the Ideal 90 H......n........ fault code mean?

Your boiler's electrical power supply has been connected with the live and neutral wires swapped, which is preventing the system from detecting the flame safely.

Also written as 90HN — same fault.

The Ideal 90 H......n........ fault code means: your boiler's electrical power supply has been connected with the live and neutral wires swapped, which is preventing the system from detecting the flame safely.. It appears on 1 Ideal model in our database.

Technical description: PHASE REVERSAL

Typical repair cost £100-200 (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 90 H......n........ fault code

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

Isar M30 / M100 Repair: £100-200

Source

Ideal 90 H......n........ 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