Hey guys,

So earlier today I started up my 2001 XJ Sport, and noticed it idling pretty rough. Now it does this from time to time, and it usually smooths out, and while this was a little rougher than usual, it still settled itself after running a bit. The only problem was the check engine light was on.

So I got home, ran through the "hold odo reset and turn on" procedure, it went through the test, but ended up just showing mileage. Tried the on-off-on-off-on, with no luck. Then I found a post that said "hold odo reset, turn on then back off." When I did that, I got a 2.5 to show up in my odometer.

Now, according to the ODS I codes, that's an AIS fault, which makes sense given the rough idling, but (and this is my first question), I thought an '01 Cherokee would have ODS II codes?

Anyway, I assumed that I was reading the code right, popped the hood, found the motor (I think, the circled thing in the picture), unplugged it and replugged it. Fired up the Jeep, and no more check engine. So I'm assuming I fixed it, but when I run the diagnostic (same one I did above, odo reset + on-off), I still get the 2.5 code.

Would I still get the code if the error were indeed reset?

Sorry for the long first post, trying to get started doing my own work on this thing, and just want to make sure I know what I'm doing.

Thanks guys.

 

How does it run now?

 

Runs fine, but even when the light was on it was idling fine. It was only rough that first time when it lit up.

I figure everything's settled, just wanted to check with people with more experience.

 

The "key-on, key-off" technique for pulling codes will NOT work with an 01. All you get is a cluster self test. So don't try to extrapolate a code from that.

You will need a code reader or a scan tool to pull the codes on your 01.

Autozone does this for free, some other stores may as well.

Even if the check engine light goes out, there will still be a stored code and you need to know what that code is as it is very likely related to your rough idling symptoms.

You really need to get the code. Your Jeep is telling you something and the code is the only accurate way of finding out what that is....Use the technology provided to you by your Jeep.

Post the EXACT code (not just a description) here for comment.

 

Good call on that.

I took it to autozone and got a P0303 Cylinder 3 misfire. Did a little research and found out about the heatsoak issues and ways to fix it. For now it seems fine, if it gets to be a frequent issue this summer I'll try out some of the recommendations on here.

Thanks guys

PS - WTF on not being able to read codes on a 2001? They had to go and add a little inconvenience to the Check Engine light, didn't they...

 

The 00-01 are the most susceptible to heat soak and if this happens infrequently and more often when outside temps are warm, then this is probably what is happening.

Yea....sometime in 97, they took the ability to use "key-on, key-off" away from the 4.0. But it is better to get the entire code using a scan tool or a code reader as the "key-on" only gives you a 2 digit code. Need the complete P0XXXX code to diagnose efficiently.