High Lockout
08 on Glow-worm Xtramax HE

Your boiler's hot water storage tank sensor has developed a fault and can no longer accurately read the water temperature.

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

TEMPERATURE ON STORAGE VESSEL: CIRCUITS OPEN OR SHORT CIRCUIT. CHECK RESISTANCE OF THE THERMISTOR.

What causes this fault?

This fault happens when the electronic sensor responsible for monitoring the temperature inside the hot water storage tank fails or loses its connection to the main control board. The most common reason is the internal degradation of the thermistor's electrical resistance over time, or moisture causing a short circuit in the wiring harness.

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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