Months ago I installed a crankshaft sensor on my 2000 Jeep Grand Cherokee, but it didn't come with a paper spacer. I recently changed my fuel injectors and there were no codes, they cleared automatically. Recently my scan tool comes up with P1391 could this be that the spacer is m

From what I've seen only Mopar sensors have that spacer. It's designed to set the proper distance from the tone ring on the flywheel and it gets torn off on startup. They are made with neodymium magnets for a strong magnetic field to last a lot longer than aftermarket ones.

Since you have a Grand Cherokee (which is not a Cherokee and not an XJ), your post should be in the Grand Cherokee section. I'll flag it and a moderator will probably move it soon.


If you didn't buy a Mopar sensor (also sold under the NTK or NGK label), it's quite possible that your new sensor is going out. On this forum (and other Jeep forums) we always recommend sticking with original equipment on sensors. An alternator, brake parts, power steering pump and a billion other things can be aftermarket, but keep the sensors original, ESPECIALLY the CPS. Aftermarket versions have a terrible track record, ranging from bad out of the box to lasting a only few weeks or months.

That P1391 code comes up for either the cam OR crank sensor. Intermittent Loss of Signal. The cam sensor syncs the injector cycle to the proper timing.