Low
t - on Worcester Bosch Greenstar i

Your boiler is simply reheating its internal hot water tank because the power was recently turned off and then back on.

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

Heating the internal DHW tank (alternates with -I-). This occurs if the mains supply has been interrupted.

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

Wait approximately 15 to 30 minutes for the boiler to finish the reheating cycle.Check that your heating and hot water controls are set to their normal positions.If the code persists for over an hour, try restarting the boiler using the reset button.

Find a Gas Safe engineer
Search the official register →

Avoid the next call-out bill

Monthly cover means no unexpected bills when your boiler breaks down.

Approved partner
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

All 78 fault codes on the Greenstar i

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

Related guides you might find useful