Took my litte Z to the shop for its safety and emission inspection this week. Safety no problems, but emission (OBD) tech says none of the sensors were available. Not failed, not passed just N/A. Any ideas why? I was messing with self test on the instrument cluster and am currently tracking down an airbag issue. Unplugged battery<thought may have been the issue, but I drove it to work 80miles round trip, started the ignotion cycle about 15 times before the inspection. Any clues would be appreciated.