We just bought a used car(97 in Calif) from a dealer. We bought it "as is" but the problem is that 2 days after we bought it the check engine light came on. Upon a closer inspection I noticed an emission related vacuum line is missing. I know it didn't just fall off and I also know that the battery had been replaced. Disconnecting the battery clears any codes in the computer and also causes the "service engine" light to go out which in most instances will come back on in a couple of days unless there is a major problem. I've used this technique myself in order to passed a smog check. This leads me to believe that the dealer did the same thing although it should have failed on the visual alone. Any recourse?