How much does it cost to fix Alpha error code 59?

Typical repair cost for the Alpha 59 fault is £120-250 including labour.

59 High

Alpha 59 Fault Code

Q: What does the Alpha 59 fault code mean?

Your boiler is struggling because the electricity supply coming from your mains is not stable or is fluctuating outside of the normal range it expects.

The Alpha 59 fault code means: your boiler is struggling because the electricity supply coming from your mains is not stable or is fluctuating outside of the normal range it expects.. It appears on 10 Alpha models in our database.

Technical description: Mains supply voltage frequency block - The PCB detects an incorrect mains supply voltage frequency

Typical repair cost £120-250 (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 59 fault code

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

Source

Alpha 59 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