LaguitasA4

My code reader says that the cause of my CEL is a large leak in the evaporative system.

Where do I even begin to look.

Thanks
Eric

John535is

Do you have a fault code number?

The leaks can be from a few different sources, start with the basics
1. is the fuel cap on (and is it sealing?) - sounds like WHAT! but actually if the fuel cap is not sealing tight it will give you that code (ask my very embarrassed son!) who swore he put the cap back on.
2. Check the vacuum hoses for leaks. When you did the coolant leak at the rear of the engine, check you didn't inadvertently snap or unplug a hose, check they are not torn etc.
3. these cars have a leak detection pump and a sensor, which engine do you have, Audi tends to hide the things in different places.