BoilerFaultCodesWorcester Bosch 357 Fault Code
The Worcester Bosch 357 fault code means: your boiler is currently running a self-cleaning sequence to remove air bubbles from the internal heating circuit, which usually happens when it is first turned on or after maintenance.. It appears on 11 Worcester Bosch models in our database.
Technical description: Ventilation program
What causes the Worcester Bosch 357 fault?
This code appears when the boiler detects that air might be trapped within the internal heat exchanger or pipework. It physically triggers a sequence where the pump runs at varying speeds to force these air bubbles toward the automatic air vent so they can be safely expelled. This process typically occurs automatically after the boiler has been drained for a repair or when the power is first turned on.
This is more common in autumn when homeowners turn their heating systems back on for the first time or after summer radiator maintenance.
DIY fix possible
Wait approximately 10 to 15 minutes for the automated program to finishEnsure your radiator valves are open to help move air through the systemOnce the countdown or message disappears, the boiler should return to normal operation automatically
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Gas Safe Register →Worcester Bosch models that show the 357 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch 357 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