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Unread 02-28-2014, 08:46 PM   #16
Mpaule
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Please see my updates to my original thread above....I am open to any ideas from anyone who has experienced this misery...

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Unread 02-28-2014, 08:56 PM   #17
Wheelin98TJ
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Has the wiring been inspected?

You have paid for a lot of work, you should not be trouble shooting, but I can understand your desire to help get the problem fixed.
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Unread 03-01-2014, 09:37 AM   #18
Mpaule
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Quote:
Has the wiring been inspected?

You have paid for a lot of work, you should not be trouble shooting, but I can understand your desire to help get the problem fixed. [/I]
Thanks..Yea I agree, but I will admit we have fixed a few things along the way that seemed to have improved performance. And thus far Jeep dealer has been fair in finding a solution - they just can't figure it out.

When you say wiring, are you speaking of wiring to CEL?..wiring from O2 sensors, or wiring in general...Only electrical problems I am aware of on Jeep currently are 1. blinker remains on after turning - which I believe is a clockwheel in steering column and 2.) once in a great while blinker "sound" will just start going without blinker on - which I have read about possible moisture issues. Any ideas on best way to check "electrical" system?

Incidentally, The CEL first appeared when we removed the cat for testing at an aftermarket shop, and drove it for a few days to ensure we were properly addressing the initial power loss issue. I think it was expected that CEL light would appear if cat was removed - but I just mention it because that's the first encounter we had with this little annoying light.

Thanks for reading and any insight you have. We may be close to finding a fix for many other CEL sufferers out there??
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Unread 03-01-2014, 02:59 PM   #19
Wheelin98TJ
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Check 02 wiring.
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Unread 03-01-2014, 04:19 PM   #20
Mpaule
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Quote:
Check 02 wiring
.

will do. dealer tells me readings on o2 sensors were doing what they were supposed to both upstream and downstream after they were replaced - thus I assumed electrical on o2 wires was working. maybe a short somewhere...
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Unread 03-05-2014, 03:26 PM   #21
Mpaule
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Today's update to my jeep....today jeep craps out on me...loss of power....whining noises. Wont go forward. Towed to Jeep dealership who couldn't troubleshoot cause of CEL prior to this happening. Not a Jeep fan at the moment. Too much stuff going wrong...no one knows how to fix it. Maybe we will see what a few days in A Jeep dealership garage with factory trained technicians and factory parts and diagnostic equipment does. hmmmm
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Unread 03-05-2014, 03:38 PM   #22
Jesse618
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What kind of o2 sensors did you get? I bought a cheap one and it tested fine, but my Jeep still ran terribly. 'Luckily' after my dad accidently broke it, I invested in a higher quality one and my problem went away. I don't want you to waste your money replacing new parts, but that's what fixed my problem.
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Unread 03-05-2014, 03:52 PM   #23
Mpaule
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Quote:
Originally Posted by Jesse618 View Post
What kind of o2 sensors did you get? I bought a cheap one and it tested fine, but my Jeep still ran terribly. 'Luckily' after my dad accidently broke it, I invested in a higher quality one and my problem went away. I don't want you to waste your money replacing new parts, but that's what fixed my problem.
Thanks for input. We first bought two O2 sensors (upstream and downstream) from AutoZone - Bosch parts. After a couple of attempts to troubleshoot CEL continually appearing, Jeep dealership said these aftermarket parts needed to be replaced with original Jeep parts. They said aftermarket O2 sensors don't work well with the jeeps. After they were replaced supposedly proper codes on both were being emitted. However, two days later cel appears. Fortunately, AutoZone was nice enough to accept parts back, and dealership was nice to discount the parts they sold me. But no one can figure this out. I am not a mechanic, but there really just aren't that many parts on a jeep for this to be so difficult.
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Unread 03-05-2014, 04:04 PM   #24
JStMarie
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At a minimum, buy a scanner. If you are going to purchase a 16 year old vehicle, you need to be prepared to deal with issues, and having a scanner is a good start. One fix can, and sometimes will, address one code only to reveal another so it isn't good enough just to know a code exists.

If you are still getting just the one code P0420 then it may be the catalytic converter was installed incorrectly or was not a correct converter. Perhaps there is a second opening left from the yahoo who first worked on it? If there are multiple codes then you need to focus on the other codes first, as the P0420 can be caused by many things and may be secondary to those issues. Or perhaps the wiring to the sensors was somehow messed up by the same yahoo?


I too own a '98, 2.5L. It currently has 220k miles on it . So don't get discouraged. They can be very reliable once running correctly.
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Unread 03-05-2014, 05:29 PM   #25
wtroger
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P0420 basically says the 02 sensors are operating to close together. As in nothing happening in the cat. Definately check the wiring around the cat. Mine had gotten on the cat and melted causing this problem. had to replace a part of that harness. Also what brand of Cat did you use. Some of the aftermarket ones don't work well. And will cause this code. The front o2 should fluctuate between rich and lean. The rear should barely fluctuate.
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Unread 03-06-2014, 07:54 AM   #26
Mpaule
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Quote:
Originally Posted by wtroger View Post
P0420 basically says the 02 sensors are operating to close together. As in nothing happening in the cat. Definately check the wiring around the cat. Mine had gotten on the cat and melted causing this problem. had to replace a part of that harness. Also what brand of Cat did you use. Some of the aftermarket ones don't work well. And will cause this code. The front o2 should fluctuate between rich and lean. The rear should barely fluctuate.
Thanks for the advice. Cat was first thing we replaced two months ago to fix power loss issue, and work was done by jeep shop, supposedly with a good reputation in Clearwater. (i.e., they know jeeps) I just called them this morning to get specs/brand on this cat so I can provide to Jeep dealer now working on it. But I would think Jeep dealer should be able to diagnose whether cat was the cause of it or not. I also asked Jeep dealer to ensure all wiring is checked today. I know I shouldn't be doing all of this research, but I just want to get it fixed. Trying to give mechanics benefit of the doubt on their troubleshooting. Hopefully, its a wiring issue somewhere - its what my son keeps telling me.
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Unread 03-06-2014, 08:01 AM   #27
JStMarie
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Quote:
Hopefully, its a wiring issue somewhere - its what my son keeps telling me.
Your profile says you are 24 years old. You're taking automotive advice from a, what, 5 year old?
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Unread 03-06-2014, 09:41 AM   #28
M-RodPRO1
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It seems that what you must be experiencing is being caused by your O2 wiring. If you just replaced the catalytic converter make sure it is compatible and installed correctly.

"There are a number of things that could be causing this p0420 catalyst efficiency code. The most common thing is the catalytic converter itself is no longer functioning properly. The other likely thing is the rear O2 (oxygen) sensor is no longer working properly. Other things could include exhaust leaks, damaged exhaust pipes, damaged O2 sensor wiring/connectors, plugged catalytic converter, etc."

P0420

Check out the link up top. It might have comments that might give you ideas. Good luck!
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Unread 03-06-2014, 01:24 PM   #29
Mpaule
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Quote:
Originally Posted by M-RodPRO1 View Post
It seems that what you must be experiencing is being caused by your O2 wiring. If you just replaced the catalytic converter make sure it is compatible and installed correctly.

"There are a number of things that could be causing this p0420 catalyst efficiency code. The most common thing is the catalytic converter itself is no longer functioning properly. The other likely thing is the rear O2 (oxygen) sensor is no longer working properly. Other things could include exhaust leaks, damaged exhaust pipes, damaged O2 sensor wiring/connectors, plugged catalytic converter, etc."

P0420

Check out the link up top. It might have comments that might give you ideas. Good luck!
Thank you for info. I did just find out cat installed two months ago was a Walker Universal - direct replacement recommend. So it shouldn't be the cat. Hopefully its just a wiring issue, but I should find out later today from the dealer. My instincts are leading me to believe its the Power Control Module, but I hope not. That could explain both power loss and codes. Thanks again for help.
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Unread 03-06-2014, 05:05 PM   #30
rockaholic18
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make sure that you don't have any intake manifold leaks or anything. the dealership should have also monitored the o2 sensors to ensure that they are not "mirroring" each other, i know on the walker universal cats you have to drill and weld an o2 bung on the cat, so if and when they welded it they may have a leak right there where they welded it at, if it were done poorly.
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