Low
CC 800 on Worcester Bosch Greenstar 30i

Your boiler has lost communication with the outside temperature sensor, which means it cannot automatically adjust its performance based on the weather.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

Outdoor sensor defect available when accessory outdoor sensor is connected

Shared across the range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Locate the external weather sensor on your outside wallCheck for any obvious damage to the sensor or its wiringPress the Reset button on the boiler control panel

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