BoilerFaultCodesWarmhaus E90 Fault Code
The Warmhaus E90 fault code means: your boiler has detected an issue with how it mixes fuel and air for combustion, meaning it cannot operate safely or efficiently.. It appears on 1 Warmhaus model in our database.
Technical description: Error in regulating combustion – possible error with the calibration values chimney gas valve and board.
What causes the Warmhaus E90 fault?
This fault occurs when the boiler's internal computer loses the ability to correctly balance the ratio of gas and air needed for a clean flame. It is usually triggered by a communication failure between the main control board and the gas valve, or because the internal sensors have detected that the combustion quality has drifted outside of safe limits.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Warmhaus models that show the E90 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Warmhaus E90 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