High
MAIN FLOW SWITCH CLOSED on Ariston Egis 24 MFFI

Your boiler thinks water is moving through the pipes when the pump is actually off, which is preventing it from starting up safely.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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

Indicator in TCS flow chart

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

A03View →

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