BoilerFaultCodesWorcester Bosch 73 Fault Code
The Worcester Bosch 73 fault code means: your boiler's internal pump or motor is not receiving power or has stopped working, meaning it cannot circulate heat through your system.. It appears on 1 Worcester Bosch model in our database.
Technical description: Faulty motor or electrical supply to motor
What causes the Worcester Bosch 73 fault?
This fault occurs when the boiler's internal pump fails to move water, which prevents heat from leaving the unit and reaching your radiators. The most common reasons are a physical blockage or mechanical failure within the pump motor itself, or a communication issue where the main control board is unable to send electricity to the pump.
This fault is frequently seen at the start of autumn when systems are turned back on after sitting idle all summer, which can cause the pump internal parts to seize up.
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 73 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch 73 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