Test pipe and a O2 bung. You could go with a Walker replacement or even better a aftermarket which might be even cheaper.
I think you just sealed it for me, THANKS! Yes I do have 2.4 Ecotec garbage engine. I had a cracked exhaust manifold at 80,000 when they did the warranty work and replaced it. I would not be the least bit surprised if it is broke again since this is a common problem on the 2.4 Ecotec. I am taking it to the dealer Saturday and they are going to do a full diagnostic to make 100% sure it is the CAT and not some other part. If the manifold is cracked I will replace that too. Of course when I did it the first time the manifold was $90, now it is over $200 SMH. You mentioned you have replaced these CATS. I am looking online and this seems to be the newest part number and does look correct, but does this look like the ones you've replaced?
2010-2014 GM Converter & Pipe 19418921 | OEM GM Parts
2010-2014 GM part # 19418921 - Converter & Pipewww.gmpartsoutlet.net
I have a dealer credit so its only going to cost me $40 to have them do a full diagnostic. Yeah I have a $50 scan tool that can do some live data, but If I am going to shell out north of $1000 I want to be 100% sure it is the cat and not something like a cracked exhaust manifold (doubtful). That being said I may hook up the scanner tomorrow and get some live data info from the 02 sensor. Thanks again.That looks about right, but it's been a while now that many of that gen have been scrapped or are too beat up to be worth this particular repair.
Do you have any data logging available to you? Such as a scanner that can show live data? No need to take it to the dealer, all one needs to watch is the output voltage of the post-cat O2 to condemn a cat. Ok, ok, to be specific one should also verify that the fuel trims while at warm cruise are within the +/- 10% range generally accepted in the field. Assuming those numbers check out, and given you've replaced both O2 sensors, just replace the cat on faith.
Isn’t there TWO cats? Front & rear? Hopefully only one is bad.I think you just sealed it for me, THANKS! Yes I do have 2.4 Ecotec garbage engine. I had a cracked exhaust manifold at 80,000 when they did the warranty work and replaced it. I would not be the least bit surprised if it is broke again since this is a common problem on the 2.4 Ecotec. I am taking it to the dealer Saturday and they are going to do a full diagnostic to make 100% sure it is the CAT and not some other part. If the manifold is cracked I will replace that too. Of course when I did it the first time the manifold was $90, now it is over $200 SMH. You mentioned you have replaced these CATS. I am looking online and this seems to be the newest part number and does look correct, but does this look like the ones you've replaced?
2010-2014 GM Converter & Pipe 19418921 | OEM GM Parts
2010-2014 GM part # 19418921 - Converter & Pipewww.gmpartsoutlet.net
I think there might be, but according to the Special Coverage 15810 it is the cat I posted above that generally goes bad.Isn’t there TWO cats? Front & rear? Hopefully only one is bad.
I have a dealer credit so its only going to cost me $40 to have them do a full diagnostic. Yeah I have a $50 scan tool that can do some live data, but If I am going to shell out north of $1000 I want to be 100% sure it is the cat and not something like a cracked exhaust manifold (doubtful). That being said I may hook up the scanner tomorrow and get some live data info from the 02 sensor. Thanks again.
I will run the live data tomorrow and report back. Thanks again sir.Even $40 is a waste in this case. If you had a cracked manifold backed by a functioning cat, you wouldn't be seeing a P0420. If anything, a cracked manifold would mask a failing cat.
I don't mean to downplay the relevance of proper diagnostics, but in this case I'm confident that your cat is the issue. The PCM logic is fairly simple when it comes to assessing cat function: while cruising at a steady load, warmed fully, assuming all other parameters are within limits, if the primary and secondary oxygen sensor output signals more or less match then you've found your issue.