BoilerFaultCodesWorcester Bosch BC Fault Code
The Worcester Bosch BC fault code means: your boiler has shut down because it is not burning fuel efficiently or safely, which is usually caused by a faulty internal sensor or an incorrect gas mixture.. It appears on 1 Worcester Bosch model in our database.
Technical description: Combustion settings incorrect
What causes the Worcester Bosch BC fault?
This fault occurs when the boiler's internal monitoring system detects that the flame is not burning at the correct intensity or stability required for safe operation. The most common reason is that the sensing electrodes have become worn or dirty, preventing the boiler from 'seeing' the flame even if it is lit. It can also be triggered if the gas valve is not delivering the precise amount of fuel needed for clean combustion.
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 BC fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch BC 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