High
4.8 on Ideal Logic Max Combi

Your boiler has detected an issue with the sensor that monitors the temperature of the water leaving the unit, preventing it from heating your home 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.

What the manual says

Manufacturer manual

Flow Thermistor Fault

From this model's manual
Verified against the Ideal Logic Max Combi installation & service manual.
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 system receives an incorrect or missing signal from the sensor that monitors hot water leaving the unit. The most common reason is that the sensor has physically failed or developed a loose electrical connection, meaning the boiler can no longer safely regulate its temperature.

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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