Medium Warning
A-b4 on Worcester Bosch Greenstar 8000 Life/Style

Your boiler has detected an issue with the sensor that monitors the temperature of the hot water leaving the unit, which may result in inconsistent water temperatures.

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.

Technical description

Hot water temperature: Outlet temperature

What causes this fault?

This fault occurs when the boiler's internal computer receives an implausible or missing signal from the sensor that monitors your hot water. The most common reason is that the sensor has developed an electrical fault or has become corroded, preventing it from accurately telling the boiler how hot the water is. In some cases, the issue may be caused by loose or damaged wiring connecting that sensor to the main control board.

Engineer required

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

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Related fault codes

A-b2View →

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