Worcester Bosch Boiler F0 Error Code

Internal control fault on Worcester Bosch boilers.

Worcester Bosch All Worcester Bosch boiler codes

May need a pro

The boiler's electronics have detected a fault in themselves. Worcester's engineer booklet gives a faulty PCB as the cause, and depending on the case the boiler either blocks or locks out.

Compatible models

Greenstar CDi Classic ErP combis, CDi Classic system and regular boilers, and HighFlow 440CDi and 550CDi ErP models.

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.

How to fix
When to call a pro
Parts
FAQ

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 F0

Reset once
Hold reset for 3 seconds. If that doesn't clear it, switch off at the spur for a minute and try again.

When to call a technician

If F0 keeps showing, the PCB needs testing or replacing by a Gas Safe engineer.

Parts linked to F0

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.

PCB (main control board)

Frequently asked questions

Which Worcester Bosch models show the F0 code?

Greenstar CDi Classic ErP combis, CDi Classic system and regular boilers, and HighFlow 440CDi and 550CDi ErP models.

Can I fix Worcester Bosch F0 myself?

Only the outside checks above. If they don't clear F0, 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