BoilerFaultCodesWorcester Bosch C0 Fault Code
The Worcester Bosch C0 fault code means: your boiler is having trouble controlling the flow of water through the system, which is likely affecting your hot water or heating performance.. It appears on 1 Worcester Bosch model in our database.
Technical description: Flow regulation valve
What causes the Worcester Bosch C0 fault?
This fault occurs when the internal motor fails to accurately control the water flow through the heat exchanger, preventing the boiler from managing temperatures correctly. The most common reason is that the mechanical valve has become stiff or seized due to a buildup of debris, or the electronic motor that turns it has failed.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Worcester Bosch models that show the C0 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch C0 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