Low
5 pulses / No light on Worcester Bosch Greenstar 24i / 28i Junior

Your boiler has been accidentally switched into a specific testing mode used by engineers, rather than having a mechanical breakdown.

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 blue 'Service' button on the front control panel.Press and hold the 'Service' button for several seconds.Wait for the indicator light to stop flashing and return to its standard display mode.

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Boiler cover options

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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 pulses5 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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