I have a 2004 Cadillac CTS with 161000 miles on it. The repair issues (computer malfunction and catalytic converter failure) will be around $3000 to repair. I just bought a new car and was going to sell this Cadillac to a friend for $2500 but the repairs are more than its worth to sell. Should I scrap it? Fix it and lose money? Any advice?

If the person you planned to sell it to is a real friend, ask him what he would like to do. This failure could have happened to him 5 minutes after you signed the paperwork. Maybe he would be willing to share the cost with you. Also, $3000 might be able to be reduced depending on the shop you use. See if you can get the work done cheaper. The car will last well past the 161K it has on it now. Instead of scrapping, why don't you just give it to the proposed buyer and let him pay the repair bill.