Help! Catalytic converter replacement

[TomP]

My 06 V has 40K miles on it and the cat code is present when check engine lite comes on. I bought the car 2 months ago so I dont have the detailed history to know if a history of misfires or something might have poisoned the cat prematurely. I drove the car 1500 miles after getting it before the CE lite came on. After Reseting it, it now comes on in a few 10's of miles. Just had it at a dealer. They said O2's are ok, no exhaust or intake leaks found, they say replace the cat. So that is why I am resurrecting this older thread. I see a lot of youtube guys saying many things can be causing this, so dont use the "big hammer" right away (ie: replace cat). Even though the car is 14 yrs old its hard for me to believe a cat can be toast already, seems a leak is more likely. But the dealer says not, so maybe I am just in denial. Any experience shared on this is welcome.

 

[shavdog]

When owners on here say they replaced the stock exhaust with Corsa, do they mean just the exhaust including mufflers but NOT the exhaust manifolds that I guess house the cat. converter.....this is different for me as the only cat. converter I have seed is withn the exhaust system....sounds like no easy fix for the cat. converter problem?

 

[mickeytee]

yes the corsa is just what is called cat back. so behind the catastrophic convertor. many cars just have cast iron manifolds with a muffler shaped cat in the exhaust system XLR has the cat built in to the manifold and is a rather drawn out process (read expensive) 40K sounds really low mileage for a failed cat but they need to get up to temp to work and someone that just drove to the store or work may not have gotten them sustained hot enough for them to work properly. Run the best gas you can for a while and try a can of cataclean. I dont recommend it as I have never used it but there are mixed reviews on you tube about it , as mentioned sometimes you can trick the cats with a foiled spark plug adapter to move the sensor out of the main stream. Of course all of this may not fix the problem but then 50$ to try is rather cheap. I think the car needs a good spirited drive of 50 to 100 miles with premium sunoco or Bp straight gas for a while see how it works. nothing really to loose

 

[richardyoo]

just an FYI - Magnaflow makes after-market cats that are less expensive than the OE versions...

 

[mickeytee]

I think a couple of posts a while back said they did not fit. so check it out before you buy
they are the cheapest at rock auto. about 1000 for the pair

 

[richardyoo]

I think a couple of posts a while back said they did not fit. so check it out before you buy
they are the cheapest at rock auto. about 1000 for the pair

I re-read this entire thread.... I do not see where anyone says this.

TomP says he has an 06, and there has been no fitment issues for 06 and magnaflow cats AFAIK

Please point us to the post where there are fitment issues for 06 and Magnaflow cats so we can all be informed.

 

[mickeytee]

They should fit as they are a good bit higher in price than the others available. I just remember a post and I did not say it was this stream, that someone had to re-drill some holes. I tried to search the forums bu tits not showing up and I dont have time but I will find it. . Maybe it was stand alone headers but I have never seen any of those. I dont think magnaflow is c.a.r.b. approved so several states use that as an emissions standard. I know they are not on the vettes but we dont have a standard to go by here Check your state before you buy to get the proper ones.

 

[TomP]

Merry Xmas and thanks for the replies. I just reviewed the paperwork I got from the dealer on this visit. Says they tested O2s (OK) and actually included the data graph and yeh, the voltage is erratic. A new visit to Youtube Scotty Kilmer discussed the exhaust pressure test kit to diagnose cats. This looked very interesting to me and I don't see in the paperwork I have that the dealer tried this. Procedure is to remove the upstream o2 sensor and screw in the pressure test gauge. Start the engine and read the pressure. Should be 0.5 psi or less, higher indicates clogging has started or is heavy, depending on what you read. 3-5 psi and the cat is definitely clogged. The gauge kit is like $50 or less so I might try this. Or look for a shop to try it for me. If not clogged, the cat should be working. Unless the cat innards disintegrated and are in the muffler. ANother youtube says to check temp at input and output of the cat. Temp should be close to same in both places, if much higher at the front its indication of clogging. I have a laser temp tool, So I have some experiments to do befiore the big hammer.

 

[shavdog]

So as I read this, if you end up with this problem, these are the possible fixes

Take it to the dealer, they remove the engine and replace and you get a second mortgage to pay

Order Magnaflow replacements(includes the exhaust manifold and cat) and either you or a shop installs

Have a shop cut off the original cats and weld in generic ones...

Have someone gut the cats and move on.....sounds illegal

Throw away everything and install headers

I probably missed some fixes...

 

[TomP]

There is also :
Rock Auto parts and shade tree mechanic (AKA: Me),
Independent mechanic using parts they may be able to get (maybe rock auto parts too).

RA parts are $613 per side. Half the cost of OEM at the dealer.
BTW, the dealer wrote the estimate for them to do it is $1700-1900 P&L.
I dont think I will be looking to change anything out till I have pressure test results for the cats.

 

[Grosguibou]

Engine check light came on, checked codes and got P0420, Catalytic Converter low efficiency. Reset the code and have been driving for couple days with out light coming back on. Mechanic suggests that since I do a lot of very short trips to get it out on the road and really get the system heated up, but he cautioned that may not fix the problem. Replacing the Cat with a OEM requires replacing the manifold and doing that requires pulling the engine. Estimated work time 16 hours plus about a 800 dollar item.

Has anyone replaced the cats with welded in universal ones, and is there even room to do it?
Any suggestions would be appreciated.

Thanks JIM

Add cleaner for catalytic converter in gas tank before try that

 

[TomP]

Here is the review I gave on amazon for CATACLEAN. A fuel additive for cleaning emissions parts. Techron helped me get the p0420 code to come and go every few tens or hundred miles but cataclean was the big hammer that allowed the check engine light to go off and stay off. 360 miles and counting. Had to share cause cats are so dang expensive on these cars. If your cat internals are not melted down, but just on the edge, this might work for you. U need to be sure all causes of any other codes that might be present are diagnosed and repaired first, else the affect of cataclean will be temporary.

5.0 out of 5 stars Cataclean had an immediate and positive affect on my vehicle
Reviewed in the United States on April 27, 2021

First, I did not buy my cataclean on amazon but I needed to share how it worked for me. I have 2006 GM Nothstar V8 car with 43K miles on it today. At 40K miles the check engine light came on when it threw a P0420 OBD code (catalyst efficiency below spec bank 1). Dealer diagnosed it as needs a new cat: $2000 estimate. So of course I did a lot of googling on what might solve the issue w/o a new cat. I started putting in Techron every fill up as advised by a fiend and every few hundred miles the code and light would clear itself, then come on again in a few more miles. Yesterday I tried cataclean mainly cause it came up in my youtube que (some guy with "panda" in his name) and because I had about a quarter tank of gas in the car which is the recommended amount for use. With the check light on, I dumped the cataclean in the car and drove 40 miles on the highway. I pulled into a gas station (light still on) turned off the engine, filled up the tank (per cataclean instructions), and started the car again to leave. No engine check light. I drove 40-50 miles home and have not seen the light come on again yet. That is not many miles but I'll keep an eye on it. The point is: I put it in, drove the car, light went out. I am a believer. Your mileage may vary but if your cat is on the edge, not destroyed, cataclean may well help you.

 

[Batmobile]

Throw away everything and install headers

That's what I'm gonna need to do eventually!

I've had an indy shop gut the cat convertors since they were clogged and creating a rattling noise on acceleration. I still have the rattling noise which is extremely annoying.

What are best choices in terms of going with after market headers?

 

[mickeytee]

some call the replacement cats, headers since aftermarket ones are tube pipes with the cat welded on. never seen a straight header.

ok I see you list a V I have been told that the headers listed for a V are the same as the 4.6 but I have never had one in hand to confirm.

 

[JJL]

Jergig
I had the same problem with my 2006 v this summer. I did find out you don't have to pull the engine to replace the manifold cat. My independent shop changed it in about five hrs and the part was under $900.00. I did find out there is aftermarket headers available from magnaflow. One guy on here replaced both of his with the aftermarket magniflows and had great success. There is also a tread on here where they ran Mr gasket cat cleaner thru the car and it fixed the problem. In my case that only made the problem worse. I have the old manifold and there appears,to be something rattling around in it. When I get two working hands I'm going to cut it open for inspection. I thing I did notice in Researching this is that it is always the passengers side that goes bad. I think when all was said and done I had under 1400 in the whole job. I'm happy and the V is running perfect.
V Happy
PS If you are interested pm me and I can get you the place I ordered mine. It beat everyone by 100 bucks and freight was cheap.