How to test catalytic converters

[torquewrench]

I suspect I have bad cats, and the car is at the dealership. Bleeding cash while they diagnose.

Quick back story:
1) Car had EPC light, and exhaust tone changed to a more muffled deeper tone. Codes scanned: multiple engine misfires. A day later, engine light was flashing and running very rough. Stopped and wouldn't restart.
2) Towed car home, car would startup and run very rough. Codes scanned again: multiple engine misfire and also P0420 code (Catalyst System Efficiency Below Threshold (Bank 1))
3) Replaced coilpacks and plugs with OEM parts.
Took a video of codes showing P0420 code, and cleared codes.
4) Car ran the same after coilpacks/plug replacement.
5) Removed exhaust. Car still ran very rough and have to give it gas to keep it running. Not drivable. NO P0420 code this time. I suspect this is because I'd need to drive it to get this to show up again. Took images of the inside of the cat. I attached images for Audi. (See below)
At this point, I had the car towed to the Audi dealer. Although I have always been able to fix my own issues on all my vehicles, I'm getting too old for this. Created a very detailed 1 page sheet summarizing everything I did. and left it for the dealer.

Audi dealer let me know there were misfire codes, and they wanted to do a compression test. Passed, $240 later.
Now, they wanted to put my exhaust back on, for another 2 hours labor. Their thought is that without the exhaust backpressure, it was causing the misfires. I baulked. It ran the exact same with or without the exhaust. For some reason they still wanted to put on the exhaust. I asked them to check the cats, and they agreed. Anyone know their procedure for checking the cats? I want to familiarize myself with the process so I can interpret their data when it comes it. Is it the same as this process (VAG-COM):

"Block 034 - Aging of Pre-Cat Oxygen Sensor
- Go to Block 034 (this test must be done in basic settings, not measuring blocks). Depress and hold brake pedal to run the automated test. The engine RPMs should raise to around 1400. Field 1 is the engine speed. Field 2 is the catalytic converter temp. Field 3 is the value which tells you how aged the sensor is (not sure what it's called). Field 4 will say either 'TEST OFF/ON' before/while the test is running and either 'B1-S1 OK' or 'B1-S1 NOT OK' after the test is finished. The aging value must be above 0.80. The value for a new sensor is 1.99. The value will decrease as the sensor ages. Release the brake pedal after the test finishes.

Block 046 - Catalytic Converter
NOTE: The test in Block 034 must be done just before this test or it will NOT initiate!
- Go to Block 046 (this test must be done in basic settings, not measuring blocks). Depress and hold brake pedal to start the automated cat. test (last approx. 100 secs - the cat needs to be warmed up above a certain threshold for an accurate reading - the threshold is usually 400°C). The engine RPMs (Field 1) should raise to around 1400. Field 2 is the cat. temp. This will also rise during the test. Field 3 is the cat. conversion efficiency. If the cat is good, the value should be below 0.50 at the end of the test. Field 4 will indicate if the cat is good (CAT B1 - OK) or bad (CAT B1 - NOT OK). Release the brake pedal after the test finishes."

[s4buckeye]

I had cat material that was bad and turned sideways, clogged, etc. and yours sounds like the same thing. not sure how it was ultimately diagnosed as bad cats but it took forever to get there.

this was some time back but all of what you described is similar to what happened to me. the extended EPA/emissions warranty paid for all of it.

[CELison]

Those pics prove the cat is toast. When I had my last one fail I had pictures just like the ones you took and they warrantied it. It should be noted that my car passed their back pressure test, even with the cat material lodged sideways in the cat housing. The service manager at my local dealer is awesome. I showed him the pictures I took and his response was something like "Oh shit man, that's not good" and had it back to me with a new cat 2 days later. I actually watched this cat fail from my rear view mirror. Cloud of platinum dust followed by a very noticeable change is exhaust tone. I have an AWE exhaust, so it was very noticeable.

[torquewrench]

Those pics prove the cat is toast. When I had my last one fail I had pictures just like the ones you took and they warrantied it. It should be noted that my car passed their back pressure test, even with the cat material lodged sideways in the cat housing. The service manager at my local dealer is awesome. I showed him the pictures I took and his response was something like "Oh shit man, that's not good" and had it back to me with a new cat 2 days later. I actually watched this cat fail from my rear view mirror. Cloud of platinum dust followed by a very noticeable change is exhaust tone. I have an AWE exhaust, so it was very noticeable.

Thanks for the info. I think I'd need to scope the inside of a new cat to compare to show them how the inside is supposed to look. I already printed out the images above for them, but they essentially ignored them and continue to try to test everything else except the cat. My guess is today they come back and say ' the cats seem good', and try to test the next item that will cost a few hundred. I feel like I have to guide them on this, so I want to know everything I can about testing the cats.

[torquewrench]

Anyone know what the exhaust pressure should be at measured in the primary O2 sensor location? A google search gives several numbers ranging from 1psi -8psi

[CELison]

That's crazy that you handed them the problem on a silver platter and they ignored you. A dislodged cat is pretty much the only thing that can cause all the problems you're having. I would speak to the service manager, as you have physical photos of the problem. Anyone who looks at those pics and still isn't sure what the problem is, is a complete idiot. If I were you I would make sure to get your money back for the diagnostics when they figure out it's a bad cat if you're under 80k miles.

[torquewrench]

That's crazy that you handed them the problem on a silver platter and they ignored you. A dislodged cat is pretty much the only thing that can cause all the problems you're having. I would speak to the service manager, as you have physical photos of the problem. Anyone who looks at those pics and still isn't sure what the problem is, is a complete idiot. If I were you I would make sure to get your money back for the diagnostics when they figure out it's a bad cat if you're under 80k miles.

They just came back and said they think the cat is ok. They looked up inside and it looks good. NO back pressure test, no vacuum test,nothing. Now they insist they must install the exhaust. Again, tried to tell me that the lack of exhaust is the issue. I've asked for an updated list of codes, and am livid right now. They said I can come tow the car home and install the exhaust myself if I'd like. I feel like I'm in the twilight zone.
They also won't tell me what their next steps are. Just that they need to install the exhaust. He finally admitted that the car is noisy and they are having trouble connecting the exhaust vent to the car.

[s4buckeye]

call AoA before they close today.


/thread


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[CELison]

Yeah at this point call AoA. That's ridiculous. Make sure you get your money back for the diagnosing too. I had 2 cats fail, both completely covered, they threw in new 02s too for good measure.

[cspcrx]

Hope you get it addresses and would love to see pics of good cats for comparison sake.

[madman4you]

torquewrench I think I have similar problems right now. I will try and explain my symptoms. I will apologize in advance for poor grammar.

OK. So about 4 weeks ago I was at the track, everything was great. I was trying out my water/meth kit for the first time, and dialing it in. Ran 93 + watermeth and car ran 11.8... not bad for poor DA. Then I added some race gas and lowered the W/M. Got down to 11.7, which was decent, but I went faster last year. Anyways, the following few days, I noticed my exhaust getting louder. (I have AWE with Resonated downpipes) So I just ignored it for a few days. Then it got worst, so I went to my local shop and they confirmed the resonators were toast. I started a conversation with AWE and the warranty dept. that went on for a week or so. But in the meantime I was driving normally.

One day I was merging on the the hwy and pushed my foot down a little more then usual and the car just cut puttered after rising beyond 4k and the EPC light came on and it went into limp mode. I pulled over, shut off the car, open the door and waited a few minutes, and started it up. EPC light gone, but check engine light was on. The car drove fine at lower speeds keeping RPMS low. But this action remained.

I went home and pulled out VAG-COM and it came up with these codes:

-351 - Cylinder 2
P0302 00 [100] - Misfire Detected
-7948 - Cylinder Disabling

- 1 Fault Found:
8931 - Secondary Air Injection System: Bank 1

I cleared the codes just because, and went driving. The Symptoms repeated. This time I got more codes.

-Cylinder 1
P0301 00 [237] - Misfire Detected
-6352 - Cylinder 3
P0303 00 [237] - Misfire Detected
-6351 - Cylinder 2
P0302 00 [100] - Misfire Detected
-6371 - Random/Multiple Cylinder Misfire Detected
-6093 - Catalyst System; Bank 1
P0420 00 [096] - Efficiency Below Threshold
-8931 - Secondary Air Injection System: Bank 1
P0491 00 [237] - Insufficient Flow
-7948 - Cylinder Disabling
P130A 00 [109] - -

After changing all OEM Coilpacks and spark plugs, however the same thing happens. The car is currently in the shop as I received replacement resonators from AWE and I figure I would let the shop figure out everything while replacing the resonators.

So far the car as been in for 2 days, and the shop mentioned today that it hooked up a gauge to the cat to test the pressure and it blow up his gauge. He said he was getting a lot of back pressure from the cat on the right side, which is where the latest misfires are. This is a local Audi/VW shop that I have known for years, he tries to figure out the source before recommending replacing anything. He suspects a bad cat. But told me the cats are expensive and its about 10hrs on the books of labor to replace one. (WTF!!) So he said he wants to rig up a test pipe to try and narrow the problem down.

Do we agree its likely the cat?

[torquewrench]

torquewrench I think I have similar problems right now. I will try and explain my symptoms. I will apologize in advance for poor grammar.

OK. So about 4 weeks ago I was at the track, everything was great. I was trying out my water/meth kit for the first time, and dialing it in. Ran 93 + watermeth and car ran 11.8... not bad for poor DA. Then I added some race gas and lowered the W/M. Got down to 11.7, which was decent, but I went faster last year. Anyways, the following few days, I noticed my exhaust getting louder. (I have AWE with Resonated downpipes) So I just ignored it for a few days. Then it got worst, so I went to my local shop and they confirmed the resonators were toast. I started a conversation with AWE and the warranty dept. that went on for a week or so. But in the meantime I was driving normally.

One day I was merging on the the hwy and pushed my foot down a little more then usual and the car just cut puttered after rising beyond 4k and the EPC light came on and it went into limp mode. I pulled over, shut off the car, open the door and waited a few minutes, and started it up. EPC light gone, but check engine light was on. The car drove fine at lower speeds keeping RPMS low. But this action remained.

I went home and pulled out VAG-COM and it came up with these codes:

-351 - Cylinder 2
P0302 00 [100] - Misfire Detected
-7948 - Cylinder Disabling

- 1 Fault Found:
8931 - Secondary Air Injection System: Bank 1

I cleared the codes just because, and went driving. The Symptoms repeated. This time I got more codes.

-Cylinder 1
P0301 00 [237] - Misfire Detected
-6352 - Cylinder 3
P0303 00 [237] - Misfire Detected
-6351 - Cylinder 2
P0302 00 [100] - Misfire Detected
-6371 - Random/Multiple Cylinder Misfire Detected
-6093 - Catalyst System; Bank 1
P0420 00 [096] - Efficiency Below Threshold
-8931 - Secondary Air Injection System: Bank 1
P0491 00 [237] - Insufficient Flow
-7948 - Cylinder Disabling
P130A 00 [109] - -

After changing all OEM Coilpacks and spark plugs, however the same thing happens. The car is currently in the shop as I received replacement resonators from AWE and I figure I would let the shop figure out everything while replacing the resonators.

So far the car as been in for 2 days, and the shop mentioned today that it hooked up a gauge to the cat to test the pressure and it blow up his gauge. He said he was getting a lot of back pressure from the cat on the right side, which is where the latest misfires are. This is a local Audi/VW shop that I have known for years, he tries to figure out the source before recommending replacing anything. He suspects a bad cat. But told me the cats are expensive and its about 10hrs on the books of labor to replace one. (WTF!!) So he said he wants to rig up a test pipe to try and narrow the problem down.

Do we agree its likely the cat?

Your symptoms sound almost exactly the same as I had before things got even worse. If they disconnect the exhaust and are still getting high back pressure, then the cats are the cause for the obstruction and need to be replaced. Does your car currently run reasonably well? Mine deteriorated in a matter of days to the point it could only idle if giving it gas. Not driveable. It's still at Audi currently. They have absolutely NO common sense there. As an example, before bringing the car in, I also replaced my plugs and coils as it was quick and cheap. OEM coils, and NGK plugs. They wanted to throw away my new plugs, and charge me over $200 to put in their "OEM" plugs which are the SAME plugs. They want to bring it back to "stock"as they say, and don't seem to have any logic. I'm only still there because I think there's a good change it's my cats, and they should be covered under the EPA warranty.

Most shops need to drop the transmission to get the Cats off, hence the high labor numbers. I was quoted $4500 by an indy shop to do the jobs. (parts/labor). FYI, I found ECS tuning had some legal cats that were on sale recently. I actually purchased them, just in case I need to do the job myself.

[Loe]

madman4you, how is your coolant level? If it's low, the symptoms you described, as well as the codes triggered are not far off from my symptoms (EPC/CEL under boost) when I had a leaky s/c intercooler. If your coolant level is fine, try logging the bank 1/sensor 2 02 sensor to compare it with bank 2/sensor 2 02 sensor. The line should be relatively steady, if it deviates too much, then it would trigger that cat below efficiently code.

[madman4you]

Your symptoms sound almost exactly the same as I had before things got even worse. If they disconnect the exhaust and are still getting high back pressure, then the cats are the cause for the obstruction and need to be replaced. Does your car currently run reasonably well? Mine deteriorated in a matter of days to the point it could only idle if giving it gas. Not driveable. It's still at Audi currently. They have absolutely NO common sense there. As an example, before bringing the car in, I also replaced my plugs and coils as it was quick and cheap. OEM coils, and NGK plugs. They wanted to throw away my new plugs, and charge me over $200 to put in their "OEM" plugs which are the SAME plugs. They want to bring it back to "stock"as they say, and don't seem to have any logic. I'm only still there because I think there's a good change it's my cats, and they should be covered under the EPA warranty.

Most shops need to drop the transmission to get the Cats off, hence the high labor numbers. I was quoted $4500 by an indy shop to do the jobs. (parts/labor). FYI, I found ECS tuning had some legal cats that were on sale recently. I actually purchased them, just in case I need to do the job myself.

My car actually runs fairly normal if I keep the RPMs under 2500. It only triggers the EPC when I have a burst or heavy acceleration. But I drove the car while waiting for the new resonators and for the shop to fit me in, for about a week. No issues starting or driving as long as I drove like a 80yr.

I did see the sale for the Right side Cat which is what is suspected. I have it ready for purchase. But the shop does not want me to purchase it in case that not it. I am considering just buying one in case the sale runs out.

madman4you, how is your coolant level? If it's low, the symptoms you described, as well as the codes triggered are not far off from my symptoms (EPC/CEL under boost) when I had a leaky s/c intercooler. If your coolant level is fine, try logging the bank 1/sensor 2 02 sensor to compare it with bank 2/sensor 2 02 sensor. The line should be relatively steady, if it deviates too much, then it would trigger that cat below efficiently code.

I did not check the coolant levels. But I will mention this to the shop. Thanks. Loe,

You say yours acted the exact same? did you get the same fault codes about the misfires and cat? I am nervous because of all the mods done to the car.
and it may just be a coincident, but it happen just after using the CW for the first time.

[Loe]

My car actually runs fairly normal if I keep the RPMs under 2500. It only triggers the EPC when I have a burst or heavy acceleration. But I drove the car while waiting for the new resonators and for the shop to fit me in, for about a week. No issues starting or driving as long as I drove like a 80yr.

I did see the sale for the Right side Cat which is what is suspected. I have it ready for purchase. But the shop does not want me to purchase it in case that not it. I am considering just buying one in case the sale runs out.



I did not check the coolant levels. But I will mention this to the shop. Thanks. Loe,

You say yours acted the exact same? did you get the same fault codes about the misfires and cat? I am nervous because of all the mods done to the car.
and it may just be a coincident, but it happen just after using the CW for the first time.

Disconnect the CW to see if it comes back. Yes, if I recall, my codes were exactly the same, even down to the cat inefficiency triggered by coolant contaminating the post 02 sensor reading.

[torquewrench]

Disconnect the CW to see if it comes back. Yes, if I recall, my codes were exactly the same, even down to the cat inefficiency triggered by coolant contaminating the post 02 sensor reading.

Loe- Good information that can help us out there having issues. I would note that madman has very high backpressure, which would point to the cat in my opinion. If it is a bad cat, your scenario may be a possible root cause for the bad cat.

[soltez]

My car actually runs fairly normal if I keep the RPMs under 2500. It only triggers the EPC when I have a burst or heavy acceleration. But I drove the car while waiting for the new resonators and for the shop to fit me in, for about a week. No issues starting or driving as long as I drove like a 80yr.

I did see the sale for the Right side Cat which is what is suspected. I have it ready for purchase. But the shop does not want me to purchase it in case that not it. I am considering just buying one in case the sale runs out.



I did not check the coolant levels. But I will mention this to the shop. Thanks. Loe,

You say yours acted the exact same? did you get the same fault codes about the misfires and cat? I am nervous because of all the mods done to the car.
and it may just be a coincident, but it happen just after using the CW for the first time.

If your exhaust note suddenly changed while WOT (mine started sounding like a muffler leak at low RPM ) with those codes I'd say its a clogged cat. Somebody on the forum had his passenger cat replaced (same as mine) only to have the driver side fail shortly after. If you play on keeping the car for awhile I'd replace both or just gut em like I did

EDIT:If you plan on buying OEM cats if check availability in advance I was going to go that route but one was back ordered 2-3 weeks lowest Queensway Audi would do was around $2200.00 for the set.

[CELison]

If your exhaust note suddenly changed while WOT (mine started sounding like a muffler leak at low RPM ) with those codes I'd say its a clogged cat. Somebody on the forum had his passenger cat replaced (same as mine) only to have the driver side fail shortly after. If you play on keeping the car for awhile I'd replace both or just gut em like I did

EDIT:If you plan on buying OEM cats if check availability in advance I was going to go that route but one was back ordered 2-3 weeks lowest Queensway Audi would do was around $2200.00 for the set.

Yup. That was me

[cspcrx]

If you going to replace them why would you not go with HFCs instead of OEMs? I guess if the dealer is covering it you have no choice.

[Batman0424]

If you going to replace them why would you not go with HFCs instead of OEMs? I guess if the dealer is covering it you have no choice.

I have been experiencing some misfire issues (replaced a bunch of parts with no improvement). Originally, I was going to try to have this done through warranty, but I doubt that would work due to my exhaust, intake and concern around being flagged TD1 for this issue. The cost of the HFC isn't bad (around 700-800), but the installation cost is bonkers. For me, this has been the reason I have not been pushing to have the cats installed yet as I am still trying to be certain that the issue is the cats.

[soltez]

If you going to replace them why would you not go with HFCs instead of OEMs? I guess if the dealer is covering it you have no choice.

JHM reintroduced the HFC like two days after I put my car back together or I would have. However if your not stage 2 you may have CEL issues from cat efficiency codes.

[madman4you]

I couldn't find JHM HFCs on their website. I only found the link to the 2.0 for a A4.

Beside the price difference what will I notice if I went this route?


It seems like Cats are the issue. I'm going to check coolant level also and point him at the leaky super charger intercooler like Loe. But I might just bite the bullet and take a chance at replacing both.

[cspcrx]

The other question is what is killing the cats? Are you going to have the same issue with JHMs?

[CELison]

The other question is what is killing the cats? Are you going to have the same issue with JHMs?

There's a ton of B8s and B8.5s that have this problem. The cats being so upstream definitely doesn't help.

[madman4you]

What do you guys think of these?

They are half price vs OEM.

http://www.hottexhaust.com/Magnaflow_49135

[Batman0424]

I couldn't find JHM HFCs on their website. I only found the link to the 2.0 for a A4.

Beside the price difference what will I notice if I went this route?


It seems like Cats are the issue. I'm going to check coolant level also and point him at the leaky super charger intercooler like Loe. But I might just bite the bullet and take a chance at replacing both.

They are listed under the S5 section.


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[mrmomo313]

What do you guys think of these?

They are half price vs OEM.

http://www.hottexhaust.com/Magnaflow_49135

I'd just go with these over the magnaflows or OEM bits.. The HFC will produce a bit more noise. How much? I'm not sure. Maybe @Loe can chime in though I'm not sure if he's installed them yet.

http://jhmotorsports.com/shop/catalo...0t-p-2431.html

[madman4you]

Loe,

Let me know about the JHM ones. I don't want my exhaust note to get much louder than I have. A little louder is OK

[Loe]

Still on stock cats at the moment.

[torquewrench]

An update to my situation. My car is still at the dealer. What they have done:
1) Scanned codes
2) Compression check
2) Installed the exhaust on the car (I towed the car to them w/o an exhaust, and they thought it needed back pressure to run properly). Grrr.
3) Dealer wanted to replace all the spark plugs (I replaced all plugs before taking it into Audi with NGK factory replacements).

It took 2.5 weeks to get them to do the above and is costing a fortune. Today, I took my tools to Audi and diagnosed the problem in the lot myself. I confirmed the catalytic converter is bad doing 4 tests:
1) When starting the car, it will run reasonably well immediately then progressively get worse. (Due to pressure building between the engine and cat)
2) I connected a vacuum gauge. At 2K RPM, the vacuum will read 15, then get progressively lower to 8. (It should hold steady)
3) I removed the O2 sensor and started it up. This gave the exhaust a place to go, and it ran great.
4) I took a look with a borescope and it appeared the inside honeycomb of the cat was partially blocked.
5) I then did a back pressure test by screwing in a back pressure gauge into the O2 sensor hole. The pressure was so high the needle went all the way around the gauge and back.

So, I can make the car run well and confirmed the cat is the issue. Now, the fun part. I had the service adviser get the tech and come to verify the issue. The tech wouldn't come, and simply had a message for me" the cat isn't the issue." They now want to check the timing next because that's what their "hotline" tells them to do. Yes, seriously. I asked for the manager since I need to move forward and have this covered under the EPA warranty. Hoping for some common sense.
His response is he would need a P420 code to replace. The crappy thing is, I had a P420 code before I brought the car in, and even took a video of the scanning and P420 code before I cleared the codes. Now, the P420 code will not manifest since the car is not driveable.
Audi of America hasn't been much help so far. They are going to look into it further but said they cannot promise me anything. They also said any diagnostics would not be covered.

[madman4you]

That's rough torquewrench , you solution with the back pressure guage is exactly what my mechanic did, and the first time he rev'D too high and it blew up his guage. On went another guage so that he could show me. He tried multiple test, and said everything leads to cats at this point. I had no leak in the coolant, levels were fine.

So this morning I went ahead and ordered the JHM cat pipes. I paid for faster shipping, so hopefully I see the early next week.

The mechanic said he will do his best to try easy on me for the bill. As he will be replacing, both cats, both resonators and 02 sensor.

My wallet will feel this one.


Keep us updated torque on what happens. If I get mine replaced before you get yours figured out, I will report back.

[cspcrx]

WOW what a pain in the A$$!

[jsh139]

That is such BS. The ineptitude of people never ceases to amaze me. Hope you get it sorted out soon.

[Loe]

An update to my situation. My car is still at the dealer. What they have done:
1) Scanned codes
2) Compression check
2) Installed the exhaust on the car (I towed the car to them w/o an exhaust, and they thought it needed back pressure to run properly). Grrr.
3) Dealer wanted to replace all the spark plugs (I replaced all plugs before taking it into Audi with NGK factory replacements).

It took 2.5 weeks to get them to do the above and is costing a fortune. Today, I took my tools to Audi and diagnosed the problem in the lot myself. I confirmed the catalytic converter is bad doing 4 tests:
1) When starting the car, it will run reasonably well immediately then progressively get worse. (Due to pressure building between the engine and cat)
2) I connected a vacuum gauge. At 2K RPM, the vacuum will read 15, then get progressively lower to 8. (It should hold steady)
3) I removed the O2 sensor and started it up. This gave the exhaust a place to go, and it ran great.
4) I took a look with a borescope and it appeared the inside honeycomb of the cat was partially blocked.
5) I then did a back pressure test by screwing in a back pressure gauge into the O2 sensor hole. The pressure was so high the needle went all the way around the gauge and back.

So, I can make the car run well and confirmed the cat is the issue. Now, the fun part. I had the service adviser get the tech and come to verify the issue. The tech wouldn't come, and simply had a message for me" the cat isn't the issue." They now want to check the timing next because that's what their "hotline" tells them to do. Yes, seriously. I asked for the manager since I need to move forward and have this covered under the EPA warranty. Hoping for some common sense.
His response is he would need a P420 code to replace. The crappy thing is, I had a P420 code before I brought the car in, and even took a video of the scanning and P420 code before I cleared the codes. Now, the P420 code will not manifest since the car is not driveable.
Audi of America hasn't been much help so far. They are going to look into it further but said they cannot promise me anything. They also said any diagnostics would not be covered.

At this point, I would have them put the car back together and drive it until the cat inefficiency code comes back.

That's rough torquewrench , you solution with the back pressure guage is exactly what my mechanic did, and the first time he rev'D too high and it blew up his guage. On went another guage so that he could show me. He tried multiple test, and said everything leads to cats at this point. I had no leak in the coolant, levels were fine.

So this morning I went ahead and ordered the JHM cat pipes. I paid for faster shipping, so hopefully I see the early next week.

The mechanic said he will do his best to try easy on me for the bill. As he will be replacing, both cats, both resonators and 02 sensor.

My wallet will feel this one.


Keep us updated torque on what happens. If I get mine replaced before you get yours figured out, I will report back.

Your mechanic may not need to drop the front subframe to uninstall the OEM pipes if they have an array of interesting tools for tight spaces. The HFC's will be substantially easier to install simply because of their smaller size. My local performance shop quoted me just a few hours (IIRC $300) for HFC install FWIW...and I asked them to double check that quote too lol.

[torquewrench]

At this point, I would have them put the car back together and drive it until the cat inefficiency code comes back.

I wish I could. The misfire is so bad that the car will not stay running after the backpressure builds up.

[soltez]

I wish I could. The misfire is so bad that the car will not stay running after the backpressure builds up.

Fwiw my car never threw the inefficiency code anything over 2500 RPM would cause limp mode.

[CELison]

I didn't throw a cat code either time I had a cat fall apart

[torquewrench]

Did a dealer replace yours under the EPA warranty? If so, did they use a back pressure test as a means to diagnose?

[CELison]

Did a dealer replace yours under the EPA warranty? If so, did they use a back pressure test as a means to diagnose?

Yeah replaced under warranty. Back pressure test the first time. Second time I just showed them the pics I took.