My 97 XJ6 failed emissions — not because it was throwing any codes, but because it showed that it had been reset. It had not been reset. Have driven the requisite number of miles to get past the "just reset" indication, but it keeps showing it has been recently reset. Have taken it to dealer. They suggested replacing oxygen sensors. Have replaced all of them. Problem persists. Any ideas? I can get a one-year exception and license plate due to all the money I've spent . . . but that doesn't solve the problem. Car runs great. No lights on. No problems. Just can't get emissions approval.

 

Sounds like you not getting past the "readiness" in OBD2. Is your battery dying? A dead battery will cause the computer to loose it readiness memory. You way want to take it for an 10 mile highway trip and get everything get hot. Does your car run cold? Since it's 1997 and OBD2 bring it to autozone and have them scan it for codes. You can also buy your own basic code scanner for about 50$.