i01 Low

Worcester Bosch i01 Fault Code

Also written as I01 — same fault.

The Worcester Bosch i01 fault code means: your boiler is not actually broken; this code simply indicates it is currently in standby mode and waiting for a signal to provide heating or hot water.. It appears on 1 Worcester Bosch model in our database.

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.

Technical description: Current status: Every operation and mode of the boiler has a related boiler status code. The boiler status code is displayed on the screen as a three figure number.

DIY fix possible

Check that your room thermostat or programmer is set to 'on'Increase the temperature setting on your thermostat to see if the boiler fires upEnsure your heating timer is scheduled correctly

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Worcester Bosch models that show the i01 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Worcester Bosch i01 fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026