How do I rectify aU9 Code?

http://gasboilerforums.com/forum/viewtopic.php?t=642

https://www.boilercentral.com/guides/worcester-boiler-error-codes/

It might be a failed pump. Safest is to get a Gas Safe certified engineer to look at it.

I think Worcester Bosch will offer a maintenance contract. You'll probably have to buy a 6 month subscription but it might be worthwhile long term.

Rkttkmtj
March 2022