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Discussion Starter #1
Hi all, I have an issue that I am hoping someone can shed some light on. I have a 1997 Jeep Wrangler SE I2.5 with 155K on it that I just bought, and kinda wishin I hadn’t. I picked up the jeep and dove it home, no codes were displayed on my INOVA scanner. next day I took it for emissions testing and it failed for the upstream O2 sensor. I swapped out the sensor and cleared the code. I drove it for 60- Miles and it would not go green (ready), it blinked the CAT was not ready, no codes set. I replaced the downstream O2 in hopes it would clear the problem and go green, no go. At this point I had put another 60 miles on it. I have read multiple forums and followed everything I could fine. I drove for 15 miles at 55 steady and have let it sit overnight twice to get good cold starts. The rig runs fine and will pull strong to 65, that’s as fast as I would go. It has new plugs cap rotor and wires. I checked all the fusses and put in a K&N air filter. All fluids have been drained and refilled, I always do that when I get a new car.
Has anybody got any insight or help?

Thanks in advance
:atomic::atomic::atomic:
 

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I replaced my pre-muffler Pipe with a new one, three cats in all... around $650.00. After I replaced the O2 sensor, reset the computer and the light came back on the following day. I'm glad I replaced it because the preheat cats (the ones right next to the engine) were almost completely used up... barely anything left in them. Expensive fix, hopefully you won't need to do that.
 

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On another note... I ended up taking it to get the emission inspection and it wouldn't show that it was ready either. I went back several weeks in a row and then the woman at the counter told me they had just received a notice that Jeep TJ's (not sure what years) had this problem and it was a wiring issue. Jeep would fix it for free. So I took it to the dealer and it took about 30 min for them to do whatever it was they did (smelled of silicone when I got back in the Jeep). They told me to drive it a few days for it to clear again, and when I took it back for the emissions test it passed.
 

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Some items are not 'ready' until they have been through a minimum predetermined number of complete cold to warm start & drive cycles. It took me a week or two of driving to get my TJ's OBDII system to show 'ready' for my state smog test after doing some smog system work. I haven't read smog system section in my FSM recently but it seems like some items can take 25 or more full cycles to make them 'ready' so the smog test can be completed. Clearing the codes with a scanner can start that whole process over again.
 

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Discussion Starter #5
Problem Solved

+OK Problem Solved. The issue was the downstream 02 sensor behind the cat. Even though it was not throwing a code and all voltages out of it were within tolerance, something was bad. Swapped it out and within a few hours it went green. Thanks for all the help from those that posted.
:iamhappy:
 
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