Medium
Ad on Worcester Bosch Greenstar 25HE

Your boiler is unable to communicate with its external hot water tank sensor, meaning it doesn't know the temperature of your water.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

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

What the manual says

Manufacturer manual

Tank sensor not detected

From this model's manual
Verified against the Worcester Bosch/Worcester Bosch Greenstar 25he installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This fault occurs when the electrical connection between your boiler's control board and the hot water cylinder sensor is broken or interrupted. The most common reason is a faulty NTC thermistor sensor that has failed internally, or a loose wiring plug that has vibrated free over time.

Engineer required

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

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Related fault codes

A7View →A8View →

All 38 fault codes on the Greenstar 25HE

Seeing a different code? Every code this model can display, in one place.

.00.01.2.2.02.42.52.63.35.05.29.324 V fuse blownA1A5A7A8ACb1C1C6d3E2E9EAF0F7FAFaultFdP1P2P3P4P6r1r2

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