Can P0430 be caused by cracked exhaust manifold?

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plext0r

New member
Hey guys, after rebuilding the transmission in my 2008 JKU a few weeks ago, the CEL came on this past weekend with P0430, bank 2. I've been hearing a strange engine noise for weeks (well before the transmission issues) and I've thought about removing the driver-side heat shield to inspect the exhaust manifold. I'm not sure how to describe the noise.

When the transmission shop pulled the codes before rebuilding the transmission, they mentioned a catalytic converter code (but didn't tell me which one) which makes me wonder about water damage. We've driven the Jeep for two weeks without any codes, then took a trip up to Gatlinburg and the CEL came on with P0430. How would you recommend troubleshooting this? Should I test the O2 sensor first?

Thanks.
 
wayoflife

wayoflife

Administrator
Staff member
What kind of sound are you hearing? It is very possible that you have a cracked manifold or a leak somewhere before or after your cat and/or O2 sensor. Of course, if you have over 100,000 miles on your Jeep, it could very well just be your O2 sensor.
 
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plext0r

New member
wayoflife said:
What kind of sound are you hearing? It is very possible that you have a cracked manifold or a leak somewhere before or after your cat and/or O2 sensor. Of course, if you have over 100,000 miles on your Jeep, it could very well just be your O2 sensor.
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The Jeep has 145K miles, but the code appeared after the transmission was waterlogged. :)

I'm wondering if the engine noise is related or something else. I'll try to grab a recording of the noise tonight when I get home from work.
 
wayoflife

wayoflife

Administrator
Staff member
plext0r said:
The Jeep has 145K miles, but the code appeared after the transmission was waterlogged. :)

I'm wondering if the engine noise is related or something else. I'll try to grab a recording of the noise tonight when I get home from work.
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But, what does it sound like? A tap tap tap sound or something more irregular?

jeeeep said:
a bad catalytic converter will make noise, sometimes they sound like marbles in a can
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This ^^^
 
Havoc40

Havoc40

New member
Short of the visual cracked manifold. You really need to have a legit scan done to read what the sensors are actually doing. Otherwise, you're just going to throw money at the problem in hopes to fix it. That should point you at either the O2 or catalytic as well.

That said, at roughly $100 for diagnosis vs. $60 for the O2, you can gamble on the odds. If it doesn't fix it, at least you have a new O2.
 
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plext0r

New member
wayoflife said:
But, what does it sound like? A tap tap tap sound or something more irregular?
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I do hear a tap-tap-tap sound especially when I start the vehicle and put it in reverse to back out of the driveway. I just changed the oil for the first time since we bought it and I used 5W20 Castrol Synthetic Blend.

I also hear a constant unwavering noise (loose heat shield?) when driving down the road especially when I drive under a bridge and the sound reflects. I believe I have two different noises and I need to dig into each one and figure them out as well as the P0430 code.
 
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plext0r

New member
Havoc40 said:
Short of the visual cracked manifold. You really need to have a legit scan done to read what the sensors are actually doing. Otherwise, you're just going to throw money at the problem in hopes to fix it. That should point you at either the O2 or catalytic as well.

That said, at roughly $100 for diagnosis vs. $60 for the O2, you can gamble on the odds. If it doesn't fix it, at least you have a new O2.
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I have a Bluetooth OBD dongle and Torque on my phone. Will Torque show the live O2 readings and could I use it to perform the diagnosis? I've only used it to monitor basic temps and speeds so far.
 
WJCO

WJCO

Meme King
plext0r said:
I have a Bluetooth OBD dongle and Torque on my phone. Will Torque show the live O2 readings and could I use it to perform the diagnosis? I've only used it to monitor basic temps and speeds so far.
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You need to be able to access the o2 data and watch the sensors switch from 0 to 1 volt. If one is stuck, it won't switch at all and reading will be stationary.
 
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plext0r

New member
I grabbed a video and uploaded it to Youtube if anyone could help me diagnose the noise. I have not yet removed the heat shield to inspect the exhaust manifold, but now that I know how to identify the pre-cat and upstream O2 sensor, I do hear a strange noise when I place the mic inside the wheel well near the driver's side pre-cat (about 1 minute into the video). Is that the marble sound people have mentioned? Do you hear anything else I wouldn't recognize due to inexperience?

Thanks!

 
WJCO

WJCO

Meme King
Definitely sounds like an exhaust leak. You can buy a cheap stethoscope at an auto parts store to try and closer identify the source. If it's the manifold, you will have to pull the heat shield to see/repair it.
 
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plext0r

New member
I finally had some time to pull the heat shield today and look what I found:
20151128_120520.jpg

I ordered the exhaust manifold and gasket from SWP and will install them on arrival. How do you like the cheap repair it appears was done by the previous owner?
 
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WJCO

WJCO

Meme King
plext0r said:
I finally had some time to pull the heat shield today and look what I found:
View attachment 175410

I ordered the exhaust manifold and gasket from SWP and will install them on arrival. How do you like the cheap repair it appears was done by the previous owner?
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Looks like you have a couple broken studs/bolts too. Hopefully those won't give you too much trouble coming out.
 
Goldeneagle1LC

Goldeneagle1LC

Member
Two me it sounded like a leak and the cat is rattling. Nothing wrong with welding up the exhaust mechanics do it all the time on planes.
 
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plext0r

New member
WJCO said:
Looks like you have a couple broken studs/bolts too. Hopefully those won't give you too much trouble coming out.
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I don't believe I have any broken studs or bolts. The two missing bolts in the picture are the ones removed while taking off the heat shield.
 
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plext0r

New member
Goldeneagle1LC said:
Two me it sounded like a leak and the cat is rattling. Nothing wrong with welding up the exhaust mechanics do it all the time on planes.
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Not sure if you can see it, but there are one or more cracks right through the welds. Looks like it cracked, someone welded it up instead of replacing it, and it cracked again.
 
WJCO

WJCO

Meme King
plext0r said:
I don't believe I have any broken studs or bolts. The two missing bolts in the picture are the ones removed while taking off the heat shield.
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Gotcha.

plext0r said:
Not sure if you can see it, but there are one or more cracks right through the welds. Looks like it cracked, someone welded it up instead of replacing it, and it cracked again.
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Yeah. Welding on cast iron is tricky, I personally wouldn't do it. Plus that area gets a lot of temperature variance.
 
Goldeneagle1LC

Goldeneagle1LC

Member
Yeah I can see it on the computer but couldn't on my phone. They used the wrong rods when they welded it and most likely didn't preheat it either. I still heard a second noise in the video. Maybe just loose heat shield, but their was a rattle with the leak noise.
 
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plext0r

New member
I replaced the exhaust manifold and gasket in a few hours last night. The bolt closest to the firewall was not tight when I took off the old manifold. Getting it tightened back to torque specs was "fun". Also, I "enjoyed" tightening the two 15mm bolts from the exhaust back to the manifold since the captive nuts were gone (must have been replaced by previous owner). I still hear something funny rattle when I start accelerating, but then the tire noise kicks in and I cannot hear it any longer. The pfft-pfft sound is definitely gone.

Since I removed the negative battery connection during this process, the CEL is off. I went for a 10-minute test drive and so far, so good. :rock:
 
WJCO

WJCO

Meme King
plext0r said:
I replaced the exhaust manifold and gasket in a few hours last night. The bolt closest to the firewall was not tight when I took off the old manifold. Getting it tightened back to torque specs was "fun". Also, I "enjoyed" tightening the two 15mm bolts from the exhaust back to the manifold since the captive nuts were gone (must have been replaced by previous owner). I still hear something funny rattle when I start accelerating, but then the tire noise kicks in and I cannot hear it any longer. The pfft-pfft sound is definitely gone.

Since I removed the negative battery connection during this process, the CEL is off. I went for a 10-minute test drive and so far, so good. :rock:
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Sweet. Good deal.
 
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