High Lockout
H1 on Ideal Mexico HE

Your boiler has stopped working because it cannot properly measure the temperature of the water leaving the unit.

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

FLOW THERMISTOR ERROR

What causes this fault?

This fault occurs when the boiler's control board loses communication with the sensor that monitors the temperature of the water being sent to your radiators. The most common reason is that the sensor has electronically failed or 'drifted' out of its correct range, making it impossible for the boiler to operate safely. In some cases, it can also be caused by loose or damaged internal wiring connecting the sensor to the main computer.

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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