Low
T1 on Worcester Bosch 24i / 28i Junior

Your boiler is currently testing its ability to create a spark to light the burner.

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

Ignition test – checking the igniter spark

Shared across the 24i / 28i Junior 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

Wait for the boiler to finish its automatic test cycleEnsure your gas supply is active and turned on at the meterReset the boiler if the code remains on screen for more than a few minutes

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Related fault codes

EAView →

All 27 fault codes on the 24i / 28i Junior

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

24i28i200203208265AA1A8BCDEFF1F2Flash once per secondGHILight onNo CH function (DHW OK)No DHW function (CH OK)No lights and no functions (with demand)rET3

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