I have an '02 Xterra I bought in January of this year. The main rear oil seal was leaking on it so I took it to a local shop and had that replaced. About 2 days after I got it back, the check engine light came on. Took it back and it was throwing a code for the output shaft speed sensor. He reset it and it lasted about 3 days before the light came back on. Took it back & replaced the sensor with a new one. About a week later the light came on again, same thing. It did this 3 more times, and the last time I took it back he claimed to have checked all wiring, plugs, etc. and said the ohms on the wires were good. So he exchanged the sensor for another new one thinking we may have got a bad sensor. 3 days later, the check engine light is on again!!! Haven't had it checked yet but feel sure I'll get the same code. Has anyone ran into this before who may be able to point me in the right direction? I'm thinking it's something they didn't put back exactly right or route the wiring correctly when they put the tranny back in after the oil seal change out.