P01391

[Tobyspaw]

Ok, I'm getting an occasional 1391 code. Warmed up at a red light in gear it will just drop off a little in the RPMs. Runs fine otherwise. Do I need to worry or not? Cam or crank sensor? 2001 4.0 auto.

[xj-jake]

Could be either one Scott. I looked up the code in a 1999 FSM and it shows that cam and crank sensor can trip that code. Might be best to do some testing or at least throw the parts in the glovebox.

[Mudderoy]

I'm not saying this is the issue but that CPS is a magnet, so it can attract metal shavings that stick to it. If you've noticed a bad spot while starting or it doesn't sound right when starting maybe you have some metal shavings on the sensor.

Wouldn't hurt to take it out and check it.

Of course disconnecting and reconnecting it on top of the intake would be the first thing I would try.

You could also try clearing the ECM.

Take the positive cable OFF the battery and touch it to ground for 30 seconds.

Verify this is correct for your 2001 before doing it.