Misfire when warmed up.
 

Hey guys! Back with another question, this one more urgent because I’m going to need my car to get to work this week.

I have a 2000 Jeep Cherokee Sport, i6 4spd auto. The other day I drove to class at 7 am (13 mile drive mostly highways), was in class until 12pm, and then got back in my car. I turn it on in the parking lot and it sounds and is running fine. I let it warm up while I pull up my podcast and check how long it’ll take me to get back home. When I’m pulling out of the parking lot then it all goes to ****. It’s sputtering, wanting to die whenever I idle it, and sounds horrible. I drive for just a little longer and it seems to clear up. I had to make it home to catch a flight i had soon so I started driving on the highway. It clears up but every once in a while it would act up. I get home and park and my car almost dies in the driveway. Now it’s just sitting there and I really need to get it fixed so i can get to and from work every day. Im pulling codes p0138, p0141 and p0303 which is why I’m posting because i haven’t seen a post on here with those 3 specifically, and I’ve been at a loss for diagnosing the real problem because I’ve had no time. Also I changed the spark plugs and it didn’t seem to help much.

Thank you for any help!

P0303 - cylinder #3 misfire
P0138 - o2 sensor circuit high voltage (Bank 1 sensor 2)
p0141 - o2 sensor heater circuit

Replace the o2 sensor. Bank 1 sensor 2 is the sensor after the cat. Thanks go to CCKen for the pics.

https://i519.photobucket.com/albums/...001exhaust.jpg

Check the o2 sensor heater circuit fuse, too.

https://www.cherokeeforum.com/attach...cannotated.jpg

When was the last time the ignition system was tuned up? New spark wires, distro, and rotor?

P0303 is common i hear.. Total heat soak issue. Exact symptoms and all. Insulate the #3 injector and reset the code. Instant success for mine. Lots of threads and write ups with part numbers.. I just took a piece off the manifold heat sheild and zip tied to the injector. Problem solved...for me.
The other codes i have negative knowledge.

Also, don't buy Autozone O2 sensors or Bosch...our Jeeps hate them. Stick with NTK.