Medium Lockout
07 on Glow-worm Xtramax HE

Your boiler's temperature sensor for hot water has stopped working correctly, meaning your system cannot tell how hot the water is.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description

DOMESTIC THERMISTOR ON DHW PIPE: CIRCUITS OPEN OR SHORT CIRCUIT. CHECK RESISTANCE OF THE THERMISTOR.

What causes this fault?

This fault occurs when the internal sensor responsible for monitoring your hot water temperature fails to send a clear signal to the main control board. The most common reason is that the sensor's internal electrical resistance has fluctuated out of range due to age, or the wiring connecting it has become loose or corroded. Because the boiler can no longer safely verify how hot the water is, it stops heating to prevent scalding or damage.

Engineer required

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

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