2022 Refresh AT4 1500 Duramax 3.0 Diesel Check Engine Light and Exhaust Leak

slythetove · Oct 29, 2022

The three months was only after we started the buyback. The first six weeks before that were trips back and forth to the dealer 6 times.

Somdman · Nov 1, 2022

So they just installed a new exhaust on my truck and it is still leaking. GM has told the dealer to add Tiger Patch tape to seal the joint. Is it me or does this seem like a BS repair strategy?

slythetove · Nov 1, 2022

That's the current "fix" for leaking at the specific joint. In my case - that worked for about a week and now CEL is back on so back to the dealer it goes on Monday.

The odds of me getting 2 trucks like this should be insane but I'm starting to think there is just a very common issue here and nobody is admitting it. GM is going to eventually have to figure out what the real problem is and issue a real fix.

Somdman · Nov 1, 2022

slythetove said:
That's the current "fix" for leaking at the specific joint. In my case - that worked for about a week and now CEL is back on so back to the dealer it goes on Monday.

The odds of me getting 2 trucks like this should be insane but I'm starting to think there is just a very common issue here and nobody is admitting it. GM is going to eventually have to figure out what the real problem is and issue a real fix.

Yes that rear clamp is still leaking after the exhaust replacement. Thank you for your feedback. I just do not see the tape as a long term solution and you confirmed that.

mrlnblues · Nov 15, 2022

I posted in this thread a ways back with my 1st trip to the dealer on this issue. I am now on my 4th, they've had it a week now, I called yesterday and was told they are doing electrical testing....whatever. They did put me in a rental car though. They've replaced multiple sensors and ECM, every time light came back on the next day. Sure hope they figure it out soon, it's hard riding around in this Toyota Corolla hatchback.....

mrlnblues · Nov 15, 2022

Monte K said:
I have a 2021 High Country, 3.0l turbo diesel. At about 1000 miles, I got the dreaded CEL with a P1488 code. My dealer when thru all the required attempts to fix it; torque the particulate sensor, torque exhaust pipe clamp, add 'Tiger Tape' to the exhaust pipe joint, smoke test for exhaust leaks, replace the flex joint.....all to no avail. I was always skeptical about the exhaust leak theory. After all, how could the truck know there was a small exhaust leak to atmosphere?? In total, my truck was at the dealer service 7 times with no resolution. Each time they reset the code and the CEL always came back on within several hundred miles. I was finally able to get the regional service tech representative involved. He instructed my dealer to replace the whole exhaust system, including the cat convertor. Probably $2-3000 in parts. That has solved the problem.

Apparently there were some manufacturing variances with the exhaust pipe joint aft of the particulate sensor. This allowed a small air leak 'INTO' the pipe between exhaust pulses which confused the emission controls. A small number of exhaust pipes with this slightly defective joint all showed up with this same problem. I also had a particulate sensor that was occasionally sending bad data. This was identified using a data collector on a 10 mile drive.

I've since discussed this issue with an engineer friend who specializes in engine emission certification. He says the very first thing they do in preparing for a test run is pressure test the exhaust system and repair even the smallest leak. Otherwise, they would never get a consistent result. So, this rather implausible solution has some basis in science.

I've put about 10k miles on it since the fix and no CEL. Yea! I commend my dealer for sticking with me on this. They were carefully following the various Tech Bulletins and instructions from Detroit and always accommodated my schedule and provided a loaner car when there weren't many available at the time.

Curious to know if you've had any problems since you last post on Oct 10th?

Somdman · Nov 23, 2022

slythetove said:
That's the current "fix" for leaking at the specific joint. In my case - that worked for about a week and now CEL is back on so back to the dealer it goes on Monday.

The odds of me getting 2 trucks like this should be insane but I'm starting to think there is just a very common issue here and nobody is admitting it. GM is going to eventually have to figure out what the real problem is and issue a real fix.

I was told by GM exhaust tape is their official repair. It’s a joke man

slythetove · Nov 23, 2022

there is a new ECM calibration they applied to mine a couple weeks ago. This is working so far.

2021high1500 · Jan 10, 2023

I have 2021 3.0. Been a great truck for 90k overall. Previous issues include
1. crank no start . Took in for fix /update which resulted in in longer cranks before ignition. Very annoying. Used to almost instantly start wirh half a crank before update.
2. Had glow plug code. Wasn't Able to take to dealer before the big one.
3. Had leak starting at rear main seal. Was gonna take in for both . 11/27/2022

4. THE BIG ONE . Took in for oil change 11/30/2022 . Two days 12/2/2022 later driving started running rough within 5 miles then it quit. Wouldn't start. Towed to dealer. Engine locked up . Not sure why if something failed or low oil issue. It was using oil 1 quart per 3k miles . Took 35 days new engine . Got back 1/09/2022.

5. Next day engine light came on. P2C7A.

Going back to dealer. Not sure what to expect. But we had fairly good 90k . Dealer that did work is saying I only have warranty to 100k which gives me 10k left. Other dealers said I should have 3year 100k [on engine.

So not sure how proceed.?

How does buy back work ?

Not super comfortable with idea of after new engine only having 10k warranty

slythetove · Jan 11, 2023

First, I'm sorry you are going through it because it's always painful when your very expensive vehicle doesn't work as it should.

I seriously doubt GM is doing a buyback with 90,000 miles on a vehicle. They charge a per mile "usage" fee when they do a buyback as well.

I would be shocked if a new engine only has warranty for 10k miles but I don't know for sure.

Options to me look like:
1) try to get them to throw in some kind of major extended warranty for free or very very cheap
2) Trade it in
3) Drive it with a brand new engine

After 90,000 miles that's no longer a new truck so new truck type options aren't realistic.

Razz1379 · Jan 21, 2023

I've had my 2020 1500 SLT, AFTER 45K miles at dealer for emissions issues for the first time. After 2 weeks of waiting for clamp parts they gave me my truck back and after 1 week the ECL came back again for the same issue. GM did not cover the repair (luckly I've had after market warranty)...Tomorrow I will take the truck in for the same issue...not sure what the real problem is but until I have reached 46k nothing major happened....I will keep everybody posted.

JohanBlanco · Jan 30, 2023

New member here. I read the full thread on this topic after googling the emissions system notification. Purchased my ‘23 AT4 w the 3.0 diesel on 4-Jan-23. Today received the emissions system notification, truck has less than 1500 miles. Truck was serviced 1-Feb-23, and the tech has indicated a NOx Sensor needs replacement. The service writeup states "P22FE NOX 2 sensing element. Per DOC ID NOX sensor 2 needs to be replaced.". The part is on back order of course!

Messiah62 · Apr 28, 2023

1600 miles on my 2023 and it threw a CEL. Dealer said it was for catalytic and nox sensor.

slythetove · Apr 28, 2023

Messiah62 said:
1600 miles on my 2023 and it threw a CEL. Dealer said it was for catalytic and nox sensor.

When there is a light you can always ask OnStar to pull the codes. Just so you know exactly what they are.

mrlnblues · May 1, 2023

Update*** Took them 6 months in total but they found what was kept throwing the code! It was a hairline crack in my manifold. They replaced the manifold and 10k miles later, no code!