High Lockout
F72 on Glow-worm Flexicom hx

Your boiler has detected that its temperature sensors are giving conflicting readings or have failed, which has caused the system to stop working for safety.

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

NTC fault

What causes this fault?

This fault occurs when the boiler's control board detects a significant temperature difference between the flow and return pipes that doesn't make sense logically. The most common reason is that one of the internal sensors has either become uncalibrated or has failed completely, leading the boiler to shut down to prevent overheating. In some cases, it can also be caused by a faulty wiring connection between these sensors and the main circuit 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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Related fault codes

F73View →F22View →F23View →

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