Guides Search

Home › Worcester Bosch › Boilers › F7

Worcester Bosch Boiler F7 Error Code

Flame signal with the burner off on Worcester Bosch boilers.

Worcester BoschAll Worcester Bosch boiler codes

F7
May need a pro

The control board is seeing a flame when the burner should be off. Worcester's booklet points to dirty or defective electrodes, flue gases being drawn back into the boiler, or the PCB. It's a locking fault.

Compatible models

Greenstar CDi Classic ErP combis and HighFlow 440CDi and 550CDi ErP boilers list it in their user instructions; the CDi Classic engineer's booklet covers the combi, system and regular versions.

Also shown as

No other codes are listed for this fault.

Difficulty

Try the basic checks, but the usual fix is a technician's job.

Not sure you are reading the code right? See how to read Worcester Bosch boiler codes.

Safety first: never take the casing off a gas boiler. If you smell gas, open windows, don't use light switches, turn the gas off at the meter if you can and call your gas emergency number from outside. A carbon monoxide alarm going off means the same: switch the boiler off, get fresh air and call.

How to fix Worcester Bosch F7

  1. Switch off and leave it off

    Turn the boiler off at the fused spur and don't try to restart it. Note the code so you can give it to the engineer.

  2. Air the room if you notice fumes

    Flue gases recirculating is on the cause list, so open windows if there's any smell or your CO alarm sounds, and keep people out of the room.

When to call a technician

This needs a Gas Safe engineer before the boiler is used again. A carbon monoxide alarm or symptoms of CO poisoning: get everyone outside and call your gas emergency number.

Parts linked to F7

These are the parts an engineer usually checks for this code. They sit inside the sealed casing, so leave them to a Gas Safe registered engineer.

Frequently asked questions

Which Worcester Bosch models show the F7 code?

Greenstar CDi Classic ErP combis and HighFlow 440CDi and 550CDi ErP boilers list it in their user instructions; the CDi Classic engineer's booklet covers the combi, system and regular versions.

Can I fix Worcester Bosch F7 myself?

Only the outside checks above. If they don't clear F7, the fix is inside the boiler and needs a Gas Safe registered engineer.

Other Worcester Bosch boiler codes

Last reviewed 2026-10-21. Codes and steps can vary by model; check your owner's manual.

Sources we checked