Low Mains Voltage High

Keston Low Mains Voltage Fault Code

Also written as LOWMAINSVOLTAGE — same fault.

The Keston Low Mains Voltage fault code means: your boiler has detected that the electricity supply coming into your home is too low for it to operate safely and has shut down to protect its internal parts.. It appears on 4 Keston models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Low Mains Voltage - Contact Electricity Provider.
Typical repair cost £0-250 (including labour)

Engineer required

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

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Keston models that show the Low Mains Voltage fault code

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

Source

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

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026