Low
5 pulses on Worcester Bosch Greenstar 12Ri

Your boiler has been left in its internal testing mode, which is usually only used by engineers during a service or setup.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

Service mode switch in max position.

From this model's manual
Verified against the Worcester Bosch Greenstar 12ri installation & service manual, page 48.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this 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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