BoilerFaultCodesWorcester Bosch 5 pulses Fault Code
Also written as 5PULSES — same fault.
The Worcester Bosch 5 pulses fault code means: your boiler has been left in its internal testing mode, which is usually only used by engineers during a service or setup.. It appears on 6 Worcester Bosch models in our database.
Technical description: Service mode switch in max position.
What causes the Worcester Bosch 5 pulses fault?
This fault occurs when the 'Service' dial on the internal control board has been left in the maximum position after a visit from an engineer. It is a manual setting used to force the boiler to run at full power for testing purposes, rather than being an electronics failure. To clear it, the dial simply needs to be turned back to the normal 'off' or '0' position so the boiler can return to its regular operating mode.
This code is most common immediately after an annual service or a repair visit, regardless of the time of year.
DIY fix possible
Locate the horizontal dial on the front of the boiler control panel.Check if the dial is turned all the way to the right (maximum position).Turn the dial back to your desired temperature setting to exit service mode.
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Worcester Bosch models that show the 5 pulses fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch 5 pulses fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.
- Worcester Bosch 28i Junior manual (PDF)
- Worcester Bosch Greenstar 12Ri manual (PDF)
- Worcester Bosch Greenstar 24i Junior manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026