Medium
8/1/1 on Worcester Bosch GB162

Your boiler is struggling to complete a routine safety cycle intended to kill bacteria in the hot water system, likely because it cannot properly regulate the temperature or flow of the 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

Thermal disinfection has failed. Outlet flow during disinfection period too high, sensor lead broken or shorted, sensor connected incorrectly or defective, filling pump defective.

From this model's manual
Verified against the Worcester Bosch Gb162 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.

Engineer required

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

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