BoilerFaultCodesWarmhaus E40 Fault Code
The Warmhaus E40 fault code means: your boiler has detected an issue with the stability of the electrical power supply coming into your home.. It appears on 1 Warmhaus model in our database.
Technical description: Electricity network frequency error – fluctuation in electricity frequency.
What causes the Warmhaus E40 fault?
This fault occurs when the boiler's internal computer detects that the incoming electrical supply is not staying at a steady frequency. The most common reason is an unstable local power grid or interference from other high-powered appliances in your home that are distorting the electrical signal. If the power supply is consistent, it usually indicates that the boiler's main control board has become oversensitive or damaged and can no longer process the electricity correctly.
DIY fix possible
Turn the boiler off using the power button or at the fused spur switchWait for 60 secondsTurn the power back on and check if the code clears as the local grid stabilizes
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Gas Safe Register →Warmhaus models that show the E40 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Warmhaus E40 fault code information on this page is sourced and cross-checked against the official Warmhaus service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026