Emergency
d1 on Worcester Bosch Greenstar 35 CDi range

Your boiler is still detecting a flame even after it has been told to turn off, which may mean a valve is stuck or the sensors are faulty.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Act immediately

Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now. This fault can be dangerous if ignored.

What the manual says

Manufacturer manual

Flame detected even though appliance switched off.

Shared across the Greenstar 35 CDi 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.

Engineer required

This is a emergency severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Find a Gas Safe engineer
Search the official register →
Boiler cover options

Avoid the next call-out bill

A cover plan would handle faults like d1: no call-out fees, no surprise bills.

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.

Related fault codes

EAView →F7View →C6View →

All 19 fault codes on the Greenstar 35 CDi range

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

-ll-2 flashes3 flashes4 flashes5 flashes6 flashes7 flashes8 flashes9 flashesA7b1C6E2E9EAF7FANo code

Related guides you might find useful

Pilot light keeps going out

Older boilers: thermocouple, draught or gas supply.

Read →

When to replace your boiler

7 signs repair isn't worth it anymore.

Read →

Is boiler cover worth it?

Break-even maths on monthly cover.

Read →