Nicholas Pesa

I have a 200 Cherokee XJ 4.0L 6 cyl. This has california emmisions as well. I got the engine light come on for O2 sensors a while ago and it was Bank 1 sensor 1, and Bank 2 sensor 2 that are shorting. It was running just fine for a good 6 months though, but now it has started to run very rough, and sort of hesitate.

My first question is would someone be able to supply me with an accurate diagram of where the O2 sensors are located for cali emissions?

My next question is if I unplug them from the electrical, and drive my car will it run fine? I do not live in an area where i need to smog it or DEQ it, so registration is not an issue, but Ive been reading around where people have just unplugged them and the engine runs fine, maybe a little rich, but no misfiring or hesitating.

My engine codes are
PO135
PO141

All help is very appreciated, thanks in advance!

CCKen

PDC:





2K / 2K1 Exhaust/O2S':

Nicholas Pesa

So my exhaust does not look like that, but I'm about 90% sure this car was manufactured with Cali emissions

BlueRidgeMark

Why?

CCKen

If your exhaust does not look like this you have a Federal Emissions exhaust system with two Oxygen Sensors. An upstream O2S (1/1) and a downstream O2S (1/2).


P0135 is 1/1 O2S Heater Failure and P0141 is 1/2 O2S Heater Failure.


Your Jeep has two O2S heaters relays, one for 1/1 and one for 1/2. Both relays are powered by the O2S Relays fuse shown in the PDC diagram I posted. Pull that fuse and replace it even though it may look okay.


It is unlikely that both relays have failed simultaneously.


After replacing the fuse clear the codes and drive it several trips to see if the codes return. If they do, the only thing common to the O2S Heaters, besides the fuse is the ground for both O2S heaters, which is at the G101 ground studs on the lower left, front side of the engine. See pic.

Nicholas Pesa

I bought it from Craigslist, and the previous owner said he transferred it from Cali to Oregon himself..... Need to check vin to see history though

Nicholas Pesa

Thanks for the very descriptive answer, will be checking and changing these today and will post back on the outcome later today.

Nicholas Pesa

So I've checked my VIN, and it is federal emissions.

Other than that I checked the fuse for O2S and it was fried, and also was a 25A instead of the 20A that should have been there. I plugged the sensors back in and replaced it with the correct fuse, and it seems to be running alright after driving for only a few miles. I have yet to check those groundings though.

Other than the grounds, would other reasons for this issue be the wiring coming from the car to the O2 sensor? Just trying to check off all reasons possible. I understand that it could just be bad sensors and those need replaced all together, but I would like to check off cheaper options first.

All help is very appreciated, thanks in advance.

CCKen

If you have Federal Emissions exhaust you probably have the exhaust configuration and O2S locations shown in figures 33 and 36.




The harnesses and connectors are shown in the pic below.

I think you should visually examine the O2S harnesses for chafing to bare wires within. Someone prior to you ran in to a problem like you're having by putting a 25 Amp fuse in that 20 Amp slot, but now the situation has worsened. That fuse should not have blown.