CC800 Low

Worcester Bosch CC800 Fault Code

The Worcester Bosch CC800 fault code means: your boiler has lost communication with its outdoor temperature sensor, meaning it won't be able to adjust its energy use based on the weather outside.. It appears on 1 Worcester Bosch model in our database.

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.

Technical description: Outdoor sensor defect available when accessory outdoor sensor is connected

What causes the Worcester Bosch CC800 fault?

This fault occurs when the main control board can no longer detect a signal from the weather compensation probe located on the outside of your home. The most common reasons are moisture getting into the sensor housing or the thin communication wires becoming damaged or disconnected due to wind and garden work.

This fault is often noticed during autumn or early winter when the boiler first attempts to use more advanced heating curves to respond to dropping outdoor temperatures.

Typical repair cost £90-180 (including labour)

Engineer required

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

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Worcester Bosch models that show the CC800 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Worcester Bosch CC800 fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026