Hey guys, I searched the threads and did not find exactly what I was looking for so here is my issue.

I just bought my latest Jeep. It is a 1997 Cherokee. It runs good, engine is smooth and sounds great. The check engine light came on last week and it is code P1398. Mis-Fire Adaptive Numerator at Limit PCM is unable to learn the Crank Sensor's signal in preparation for Misfire Diagnostics.


I know if the crankshaft position sensor is dead then the engine will not start. I have found on other forums where there was a TBS for this Jeep for this problem.

http://www.jeepforum.com/forum/f9/p1...re-out-647960/

Should I replace the sensor, or take it to the dealership and have them do a diagnostic on it or trouble shoot something else first?


I called them and they said if it only needed the software update they would only charge me the $110 diag charge. I would not let them do anything else if they wanted because I am sure they would eat me alive with the $ it would cost.

Thanks in advance

 

I'd replace the CPS.. they don't always go quickly, sometimes they hang on for a long time causing intermittent symptoms. They're difficult to get to, but well worth the effort to save some $$s.

 

Did you ever find out what the problem was? What did you do to fix it?

 

I replaced the crankshaft position sensor it took about 20 minutes and the issue did not come back

 

About how much did it cost? I can't find on online from the local car parts stores.