E1 High

Ideal E1 Fault Code

The Ideal E1 fault code means: your boiler has detected that the electrical wiring coming from your home’s power supply matches the wrong terminals, meaning the power flow is backwards.. It appears on 1 Ideal model 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: Live and Neutral reversed

What causes the Ideal E1 fault?

This fault occurs when the boiler detects that the live and neutral electrical connections have been swapped at the power source or within the internal wiring. It is most commonly caused by recent electrical work in the home or an incorrectly wired plug or fused spur, which poses a safety risk to the internal electronics. Because British boilers are polarity-sensitive, the system will prevent operation until the wiring is physically corrected.

Typical repair cost £80-160 (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 E1 fault code

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

Source

Ideal E1 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