Low
5 pulses on Worcester Bosch Greenstar 24i / 28i Junior

Your boiler is currently in a manual testing mode set by the technician, which makes it run at its highest speed.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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

Not a fault code. Service mode selected to max, press service button to return to normal.

Shared across the Greenstar range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Locate the button labeled 'Service' on the front control panel of your boiler.Press the 'Service' button once to exit the testing mode.Check that the flashing light stops and the boiler returns to its standard operating display.

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All 35 fault codes on the Greenstar 24i / 28i Junior

Seeing a different code? Every code this model can display, in one place.

2 pulses2 pulses / No light2 pulses No light5 pulses / No light5 pulses No light6a1213141516171819109115A7A8b1Blue indicator light offEAERRORFAFast flashFast flash / FlashingFast flash / OffLOCKOUTNo lightNo light / Not a fault codeOff (No light)Off / OffOn / OffSlow flashSteady on (Burner lit)

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