BoilerFaultCodesWorcester Bosch 74 Fault Code
The Worcester Bosch 74 fault code means: your boiler's internal computer has encountered an error and is unable to communicate properly with the rest of the system.. It appears on 1 Worcester Bosch model in our database.
Technical description: Control box fault
What causes the Worcester Bosch 74 fault?
This fault occurs when the boiler's main control board experiences an internal electronic failure or a loss of data. It is often caused by a component failure on the circuit board itself or a loose connection in the internal wiring preventing the computer from sending instructions to the burner. In some cases, an external power surge or moisture ingress can also damage the sensitive electronics inside.
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 74 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch 74 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