What to check, in order
- Don't try to fix it yourself
Worcester's manual says not to try to put F0 right yourself.
- Call a Gas Safe registered engineer
Tell them the code on the display.
When to call a Gas Safe engineer
Worcester's service booklet describes F0 as an internal fault in the control board (PCB), which is replaced if the fault keeps coming back.
A repair visit will usually check the wiring first, then the boiler's control board.
- Note the model and serial number. They're on a label on the data badge, usually under the boiler or behind the front cover.
- Write down the exact code, and what the appliance was doing when it appeared.
- Check whether it's still under warranty. If it is, the repair may cost you nothing.
Quick answers
What does the Worcester Bosch F0 fault code mean?
The boiler's control board has reported an internal error and locked the boiler out.
Can I fix Worcester Bosch F0 myself?
Engineer only (engineer visit). Start with: don't try to fix it yourself; call a Gas Safe registered engineer. Worcester's service booklet describes F0 as an internal fault in the control board (PCB), which is replaced if the fault keeps coming back.
Is Worcester Bosch F0 worth repairing?
Get a quote first. A new control board is one of the dearer boiler repairs, so get a price and weigh it against the boiler's age.
Checked against
- Worcester Bosch Greenstar CDi Classic user instructions (PDF)
- Worcester Bosch Greenstar CDi Classic engineer's service booklet (PDF)
Last reviewed October 2026. Manufacturers update their pages, and your manual is the final word. Spotted a mistake? Email contact@appliance-error-codes.com.