Reverse polarity High

Ideal Reverse polarity Fault Code

Also written as REVERSEPOLARITY — same fault.

The Ideal Reverse polarity fault code means: your boiler's electrical power supply has been connected backwards, meaning the live and neutral wires are swapped, which prevents the unit from starting safely.. It appears on 4 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: Flash > 1/sec alternately with LED 4 and LED 3
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 Reverse polarity fault code

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

Source

Ideal Reverse polarity 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 31 August 2026