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.
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.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →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