105H High

Ideal 105H Fault Code

The Ideal 105H fault code means: your boiler is failing to start because the electrical supply wires are connected in the wrong order.. It appears on 2 Ideal models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: PHASE REVERSAL
Typical repair cost £100-180 (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 105H fault code

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

Source

Ideal 105H 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