brian0128

I recently had a no start condition on my XJ which turned out to be the crankshaft position sensor. No CEL's appeared when I got the no start condition. I replaced it with a factory Mopar replacement part 2x because the first one failed after 15 miles. I'm not sure what made it fail but I tested it with a multimeter using a write up I found on here and it tested bad.

After I put in the 2nd CPS, I have driven 800 miles in 2 weeks and yesterday on the way home the CEL came on. I used my code reader and got 2 codes. P0120 and P1391. I did not notice any change in driving or idling performance. I cleared the codes with the reader and put another 25 miles on the Jeep before the CEL light came on again. It is showing the same 2 codes. The 1st listed is P0120 and the 2nd is P1391.

I checked for any worn wires in the harnesses under the hood and also wriggled all of the connectors and wires to see if it made a difference but I haven't seen anything. Where should I start troubleshooting this one? As I said above, the Jeep is running great and I don't notice any problems except for the light. After doing some research online it looks like the codes are for the TPS and the camshaft position sensor (pick up coil). Any ideas?

dukie564

Like i mentioned last night, the only way I can think of that both those sensors would throw fault codes at the same time is a short in the wiring harness or a faulty ground.

landude

Maybe hit the connections with some contact cleaner, never know...
Another thought, pull the neg battery terminal off and let everything clear.
Maybe with the new sensor the computer is a little confused..