High
A42 on Ferroli Modena HE

The boiler's internal thermometer is sending an incorrect signal to the control board, preventing the system from heating your water correctly.

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.

What the manual says

Manufacturer manual

Flow sensor error – sensor damaged

From this model's manual
Verified against the Ferroli Modena He installation & service manual, page 26.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This fault occurs when the boiler's control board loses communication with the temperature sensor or receives a reading that is outside of its normal operating range. The most common reason is that the internal thermistor has chemically degraded over time, but it can also be caused by loose or corroded electrical connections between the sensor and the main board.

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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