How much does it cost to fix Ariston error code MAIN FLOW SWITCH CLOSED?

Typical repair cost for the Ariston MAIN FLOW SWITCH CLOSED fault is £120-220 including labour.

MAIN FLOW SWITCH CLOSED High

Ariston MAIN FLOW SWITCH CLOSED Fault Code

Q: What does the Ariston MAIN FLOW SWITCH CLOSED fault code mean?

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

Also written as MAINFLOWSWITCHCLOSED — same fault.

The Ariston MAIN FLOW SWITCH CLOSED fault code means: your boiler thinks water is moving through the pipes when the pump is actually off, which is preventing it from starting up safely.. It appears on 1 Ariston model in our database.

Technical description: Indicator in TCS flow chart

Typical repair cost £120-220 (including labour)

Engineer required

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

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Ariston models that show the MAIN FLOW SWITCH CLOSED fault code

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

Egis 24 MFFI Repair: £120-220

Source

Ariston MAIN FLOW SWITCH CLOSED fault code information on this page is sourced and cross-checked against the official Ariston service / installation manuals for each affected model.

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