High
A7 on Worcester Bosch Junior 28i

Your boiler's hot water sensor is not reading the temperature correctly, which usually means your hot water will be cold or the temperature will fluctuate significantly.

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

The hot water negative thermistor coefficient (NTC) sensor is defective – the hot water sensor or connecting leads need checking.

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

A8View →B1View →

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