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Unread 09-14-2014, 09:42 PM   #1
Jchulski19
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Catalytic Converter below threshold

My 5.7 has the famous exhaust leak at the manifold. I had the stealership check it out and they said it has 2 broken studs on the manifold which is causing the exhaust leak. Just the other day my CEL came on and the code was "catalytic system efficiency below threshold (bank 2). I just bought this jeep in january, could the leak at the manifold cause the computer to throw the converter code or is the converter actually going bad? This is kinda sad because I had to put $900 worth of converters in my old saturn and I don't want to ever have to do that again!

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Unread 09-14-2014, 11:50 PM   #2
Kolak
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It's very likely the manifold leak that's causing the code. The system is very sensitive to exhaust leaks.
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Unread 09-14-2014, 11:52 PM   #3
Jchulski19
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thats great! the dealer I bought the jeep from is quoting me $910 to fix the leak and replace all the studs but the guy i bought it from is chipping in $410 from the used car department so i only have to pay $500 in the next couple weeks
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Unread 09-15-2014, 01:11 PM   #4
90grandoneer
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Quote:
Originally Posted by Kolak View Post
It's very likely the manifold leak that's causing the code. The system is very sensitive to exhaust leaks.
X2. For some reason Bank 2 seems to be more sensitive to everything emission/fuel mixture related.. Both of my Hemi vehicles (05 LX and 06 WK) seem to read somewhat differently between Bank 1 and Bank 2, especially at low speed, with the MDS on. At idle, MDS off, or cruise, both banks are about the same. Over time, I've only gotten one DTC though. Cleared it, and it's never come back. I also had a pretty good header flange gasket leak, and had to drive it about 900 miles that way (couldn't find anyone that would tackle the fix), and never got a light. I did lose about 3 mpg over normal though.

Fix the manifold leak(s) first, clear the code(s), and then see how it goes. It would help if you have some way to monitor the O2's and the cats. I have DashHawks on both of mine. They no longer make them, but other similar devices are the DAshDaq, ScangaugeII, or the Ultra Gauge. Maybe Kolak can help you pick one of these up.

As a side note, if you can't do this repair by yourself (time consuming but recommended), you may want to look into a reputable independent or muffler shop. The dealers are almost always higher on their labor charges.
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Unread 09-16-2014, 12:21 AM   #5
Jchulski19
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Originally Posted by 90grandoneer View Post

X2. For some reason Bank 2 seems to be more sensitive to everything emission/fuel mixture related.. Both of my Hemi vehicles (05 LX and 06 WK) seem to read somewhat differently between Bank 1 and Bank 2, especially at low speed, with the MDS on. At idle, MDS off, or cruise, both banks are about the same. Over time, I've only gotten one DTC though. Cleared it, and it's never come back. I also had a pretty good header flange gasket leak, and had to drive it about 900 miles that way (couldn't find anyone that would tackle the fix), and never got a light. I did lose about 3 mpg over normal though.

Fix the manifold leak(s) first, clear the code(s), and then see how it goes. It would help if you have some way to monitor the O2's and the cats. I have DashHawks on both of mine. They no longer make them, but other similar devices are the DAshDaq, ScangaugeII, or the Ultra Gauge. Maybe Kolak can help you pick one of these up.

As a side note, if you can't do this repair by yourself (time consuming but recommended), you may want to look into a reputable independent or muffler shop. The dealers are almost always higher on their labor charges.
I have a live data scanner and the cats are getting up to temp and the o2 sensors are reading properly. I talked to a couple other places today and one shop here wants 350 out the door to replace all the studs but now I have another dilemma, should I have them replace both manifolds as well or can I get away with using the old ones?
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Unread 09-16-2014, 07:26 AM   #6
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Have them inspect the originals real closely and go from there. If this is a muffler shop, and you have to replace them, consider replacing them with Hemi LX manifolds. They're somewhat more efficient than the stock WK units. Here's a thread I did on the differences: http://www.jeepforum.com/forum/f67/b...-7-wk-1174042/

It'll obviously require a little head pipe work (minor), but should be worth a little horsepower boost.

What are your rear O2's reading while cruising at various speeds, and at idle? Are they always above .500 mV or below?
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Unread 09-16-2014, 02:54 PM   #7
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If the code is P0430....

Try the spark plug non fouler trick first before you go replacing anything expensive. There are plenty of write-ups on how to do it. About the only catch is living in a state that has emissions tests as part of the inspection. If you don't live in one of those states, I would start there first.
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Unread 09-17-2014, 12:19 AM   #8
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My upstream o2 sensor is jumping from high to low on both banks and the downstream is staying constant at about . 750 on both banks.
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Unread 09-17-2014, 10:01 AM   #9
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That is absolutely normal for both up and down stream sensors. Actually, your downstream ones work better than mine. My No. 2/2 will drop to 50-100mV when at low speed cruise with the MDS on. Accelerate, cold starts, idle, high speed cruise, it's normal. I stilll have only gotten that one light I talked about earlier. I don't know if it's a combination of exhaust flow and PCM settings (resulting from sensor inputs) or what?? I suppose mine could also have something to do with the cam timing (maybe overlap), since both of mine have aftermarket cams (WK advanced total of 6 degrees and LX advanced total of 10 degrees) I have installed in them. I do know it's not affecting my fuel economy or performance, so I am not too worried about it. If it starts causing some other issues, I'll dive into it and see if I can figure it out. Definitely let us know the outcome of this one.
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Unread 09-17-2014, 05:16 PM   #10
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I had that cel come after right I bought my jeep. Dealership changed out the right side cat and that fixed the cel. My wk hemi is at the dealership as we speak getting the exhaust manifold worked on for the same reason, leaking.
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Unread 09-17-2014, 09:54 PM   #11
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I had that cel come after right I bought my jeep. Dealership changed out the right side cat and that fixed the cel. My wk hemi is at the dealership as we speak getting the exhaust manifold worked on for the same reason, leaking.
Let me know if they replaced the entire manifold! thats kinda the issue im running into now im almost sure that the CEL was/is caused by the leak. The CEL hasn't came on since i cleared it Saturday. I still want to get it fixed tho. I just don't know if I should just order used manifolds from ebay or whether I should shell out the cash for dealer-only manifolds.
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Unread 09-18-2014, 09:47 AM   #12
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Originally Posted by Jchulski19 View Post
My upstream o2 sensor is jumping from high to low on both banks and the downstream is staying constant at about . 750 on both banks.
The upstream O2's should jump from high to low and the downstream should hover around 0.5mv(+/- 0.1mv).If the downstream O2's "mirror" the upstreams then that is when the 420/430 codes show up as the cats are not doing what they are supposed to be doing.

Downstreams sitting at 0.75mv shows your running lean,due to the exhaust leak,should actually be getting a 171/174 codes, but if you got a cat code the PCM saw a downstream O2 follow the upstream on 2 drive cycles.It can take some time for the code to pop back up since it requires 2 failed drive cycles to turn the MIL on for those codes.
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Unread 09-18-2014, 03:40 PM   #13
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I too have gotten one of these mysterious codes (p013c) 2/2 O2 sensor spoke rich to lean. Finally got a better scanner do I can watch the voltages of the downstream sensors at different speeds. At highway driving I saw them reading almost exactly the same, .6-.7v. One thing that was interesting I think I saw it do the rich to lean monitor test where it went from .9 to .1 and back, then went back to .6+- .1 or so. This was accelerating to a bit more than 60 then backing off. I have heard that they are very sensitive to minor exhaust leaks and that it is usually not the sensors but possibly a leak anywhere ahead of the sensors.
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Unread 09-18-2014, 11:23 PM   #14
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I cleared the code saturday and it hasn't popped back up for a week but i'm fixing it next week thursday. The dealer i bought it from paid for all the parts all i have to do it cover re machining (which i might do at my shop or pay for) and labor.
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