There are two cats and four o2 sensors. Bank1 is left (driver) side and bank 2 is right (passenger) side. The upstream sensor reference is (1) and the downstream reference is (2). Thus the left upstream sensor is Bank 1 sensor 1 and left downstream is Bank 1 sensor 2. So right side is upstream Bank 2 sensor 1 and downstream is Bank 2 sensor 2. Your code reader will identify which one is bad.
Before you attempt to replace any of these here's a little warning:
If you have the 4WD model, I would recommend just taking it to a professional who works on Jeeps and has experience with these, or yes, (I can hardly believe I am saying this), take it to the dealer. I have worked on cars my whole life, on my personal cars and also professionally when I was much younger, yes it's true my activities as professional mechanic ended over 30 years ago; but I can tell you that I can pull the engine out of a Ferrari Boxer and have it on stand in less time than it takes to get at the wire connections for these sensors on this Jeep.
You might want to ignore this warning and continue on, but before you do take a look at the picture and a drawing that I found in this thread. This will help illustrate the difficulty in performing what should be a fairly simple and straight forward operation. I would also like to remind you unless you have access to shop facilities most of this will be done on your back lying underneath the Jeep.
If these sensors have never been replaced, the connector side that goes with the sensor will be the extra-secure three-step disconnect type of connector. (I will get a picture of these and add it to the thread later, to illustrate). The three steps to disconnect are:
1. Slide the red locking tab towards the sensor unblocking the release button.
2. Push the release button down and hold it down, while... see 3) (Note: Holding it down is may be impossible because there is absolutely no room for your hands. What you can do if you try hard is push the button down and get the connector to slide very slightly on it self in the direction of separation so that the button stays down without pressure. Then you can move to step 3 as a separate operation)
3. Holding both ends of the connector, (so as not to put tension on the wires), separate the connector.
Hint: You may have to use substitutes for fingers such as long screw drivers, long reach needle nose pliers, long reach small jaw locking pliers etc. to maneuver around and position the connector, in order to perform the above tasks.
The connector location for both the downstream senors are shown in the drawing attached. Make note of where they will be when the engine and transmission is installed in the vehicle. They will be in about a 2 inch or less gap between the firewall and the cylinder head/engine block. Translation: not much room to work within.
Grave warning: Do not be lured into grasping the wires themselves to try and separate the connector.
The new connector end with the sensor is a two-step connector and eliminates step one because it does not have the red locking tab.
You can get easily to the right downstream sensor and remove it with a special 7/8" split socket to allow relief for the pigtail.
The right upstream sensor connector is under the right exhaust manifold and may be possible to see, but not by much from the top side, looking between the inner fender and the exhaust manifold. Once you know how the connectors work you can do this one by feel, but you may need to resort to working top and bottom and using various tools to get it disconnected.
To remove the sensor you need two people or something like it to do this:
I worked from the top and the front, using a long 18" 3/8 extension to remove and replace the sensor. The second set of hands worked from the side and guided the socket onto the sensor for removal. For installation the second set of hands started threading the sensor in and then guided the socket onto sensor for tightening. If you're by yourself you are going to have to do each loosening and tightening in two steps each. Put the extension and socket together then thread it through the obstacle course from the front then goto the side and put the socket on the sensor. Then keeping pressure on the extension to prevent the socket from slipping off, put the ratchet on, and loosen or tighten as required.
The right side is the easiest to do, and I now know: it's difficulty is just at my personal limit of wanting to do this kind of work at home.
The left side is impossible but I did change out the left down stream O2 sensor. Everything is in the way here, now you want to look at the picture to fully understand this.
The picture shows a 2002 but it is not a 4WD. From this point of view on a 4WD you can't even see the oil pan or anything else because there is crash plate frame tie-in between the two lower suspension control arms. It adds structural strength to the frameis protecting the front differential. There is the front driveshaft that runs between the transfer case and the diff. just under the starter between the cat and the oil pan.
You could see this if the crash plate weren't in the way on the 4WD. In addition the steering column driveshaft comes down just in front of the cat and would obscure the cat and the upstream sensor shown in this non-4WD view.
I could not get the socket over the sensor. I resorted to carefully using an open end 7/8" wrench. A line wrench might work better or crows foot for a line connection may work even better.
The connector for the left side upstream sensor cannot be seen from any position nor can it be touched. You can get to the sensor from the top but thats about it.
At this point I considered taking the left side motor mount bolt out while jacking the engine up. But I just gave up. Look at the picture and drawing attached here. Then go look under your Liberty and be sure you are up to the task. Do not cut any wires and don't assume that sensor you get from the parts store is the right one until you have compared the connector to the old one and are certain it matches and are also satisfied that the wire length for the new sensor also matches.
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