I think I would have change out the Catalytic Convertor the first time the code scanner said it was the problem.

I'd say the OP was scammed by the first mechanic who " cleaned " the old catalytic convertor for $300.

Heck for $300 you could probable replace everything from the cat back if you do it yourself.


EDIT: I see the OP is in California - I think the nice comrades that run that state made it all but illegal to change your own cat convertor.

 

I guess I got lucky with all the Chrysler products I've owned that were made after 1981. What year Dak? Used to have a 95 V6 5spd. By any chance you ever frequent the DML?

 

If most shops are indicating the cat. why not have it changed all these problems could be related to the cat

 

It works on my 2001 jeep cherokee loredo

 

 

Unless modified, the 2001 XJ has three catalytic converters. Two monitored "mini" converters, and one unmonitored downstream converter. If there is a converter related DTC it will be for one, or both, mini converters. See pic.

The downstream O2S's shown in the pic monitor the two mini converter's efficiency. Should there be a defective converter and is detected during the PCM converter monitoring the PCM will set a DTC and turn the CEL on. This only happens when monitoring the mini converters, not the unmonitored downstream converter.

The downstream unmonitored converter is not discussed in the FSM and it can only be surmised that its function is to aid in emission control during the period of time it takes for the converters, and O2S's, to come up to operating temp.

Some XJ owners have had luck just changing the associated downstream O2S (1/2 or 2/2), where others have had no such luck and have had to change the manifold assembly (both Cats).

The proper O2S' are shown on the pic.

 

Are they really four different sensors and non-interchangeable?

 

Yes.

Pigtail lengths, connector design, and probe design.

The upstreams have the same probe design and connector design (Gray), but different pigtail lengths.

Same for the downstream O2S'. Black connectors.

 

They luv makin dat $$$$$.

 

Was this thread really revived lol.

 

What's a few years among friends.

 

Lol. Wonder what th OP been up too

 

Hey Guys & Gals. I'm fairly new here and this is my first reply. I did the error code check on my 01 XJ Sport. holding the trip reset button and turning the key three times gives me the guage check. Just turning the key 3 times really quick gives me error codes.

One thing I have found is if I do the guage check first, the error codes will clear and I can only access them then by using the ODB2 port. So, if you try this try reading any codes first. Too, this method will not reset the CEL. Mine was on and I kept chasing vacuum leaks until finally, that one big hose that runs down the firewall to the front axle had a crack in it. Couldn't see it from top or bottom, but one could feel it (unless equipped with mechanics fingers). So, I faithfully spliced it and wa la.

 

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The front differential vent hose should not be connected to any engine vacuum source?

 

Sounds like a plugged exhaust system.

The catalytic converter can do this or cause this if it breaks up inside and doesn't pass the pieces out, and though the muffler and tailpipe.

I think the converter(s) need to be removed and inspected. Replaced with a good one if necessary. The cheap ones will continue to set off codes.