How much does it cost to fix Alpha error code E40?

Typical repair cost for the Alpha E40 fault is £100-350 including labour.

E40 High

Alpha E40 Fault Code

Q: What does the Alpha E40 fault code mean?

Your boiler has detected an issue with the electricity supply entering your home, meaning the power frequency is inconsistent and the system has shut down to protect its internal electronics.

The Alpha E40 fault code means: your boiler has detected an issue with the electricity supply entering your home, meaning the power frequency is inconsistent and the system has shut down to protect its internal electronics.. It appears on 6 Alpha models in our database.

Technical description: Mains supply frequency outside limits

Typical repair cost £100-350 (including labour)

Engineer required

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

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Alpha models that show the E40 fault code

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

Source

Alpha E40 fault code information on this page is sourced and cross-checked against the official Alpha service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026