There are several posts already in this forum which may help you.If this is not the case,you should post again with more details,particularly the X*** number for your engine and the year.CDI is really an equipment level indicator.The operation varies,depending on age and whether 8V or 16V,I can't tell from the info provided.Sorry.
If it's a diesel (which Cdi suggests it is), it's quite likely it is cam-chain, and hence will not need to be changed on a regular/scheduled basis.
cam belt
belt driven
Usually the cam belt should be changed every 60,000 miles
I believe all vauxhalls are recommended for a belt change at 40,000 miles.
When to change out a timing belt on 06 vectra sri Mileage wise
they have a chain mate
It's a cambelt.
vectra b 2.0 dtl / dth, and the same for 2.2 do not require a timing belt change as they are chain driven , however the tensioner requires checking after 150,000
Vauxhall now recommend a change of cam belt every 40,000 miles or every 4 years. The used to say 80,000/8 years but they had too many failures. Have a kit fitted, this includes the tensioners.
How often do you need to change the cam belt on an Astre 1.6 club 2000 plate
Does a vauuxhall aastra 1.4 petrol turbo have a cam belt or is it chain driven
72,000 miles or 5 years