My deal is that my niece owns a 2000 Passat. She has taken a job overseas and left it for us to figure how to get the best $$ for it... she's going to need the $$ for the next couple of months before the new jobs kicks in, etc... We would like to sell it to an individual but it has two problems that being honest like we are won't let us...

A charge on a new battery won't last more than a day... something is draining it over night...

The check engine light is on... I think that was diagnosed as Catalytic converter problem...

Any ideas on how to diagnose the battery drain... any "common" problems known...

This will probably be a great deal of a car for the right buyer if interested...

Thanks to all in advance...