I would say a refund is very unlikely. Read the fine print on the back of the sales contract.
The best you can hope for is a refund if they cannot fix the problems.
As for the problems, I would not call them 'minor'
Check engine and airbag warning lights as well as leaks can be indicative of serious and expensive problems. Were these problems evident before you bought it? If yes, did you have it written into the contract that they would be fixed?
If not, all you can to is complain a lot, and perhaps have a lawyer look over the contract and send them a threatening letter, and possibly file a small claims suit, if nothing else works.