BoilerFaultCodesWorcester Bosch C4237 Fault Code
The Worcester Bosch C4237 fault code means: your boiler's main internal computer has developed a serious electronic fault and can no longer control the heating process safely.. It appears on 1 Worcester Bosch model in our database.
Technical description: Control box or heat control module (HCM) is defective
What causes the Worcester Bosch C4237 fault?
This fault occurs when the boiler's internal computer chips suffer a critical communication failure or hardware burnout. The most common reason is age-related degradation of the electrical components, though it can also be triggered by a sudden power surge or moisture getting into the control box casing.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Worcester Bosch models that show the C4237 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch C4237 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