I have the same code and getting the 65mph speed warning. I have an appointment next week but I’m not covered under warranty. I can’t imagine the cost I’ll pay if I need to go in as many times as you.

 

 

'20 Chevy LM2. Bought used w/ 36,200 mi 2 weeks ago, put 1000 miles on it and got check engine light - P2C7A. Found this post, printed the service bulletin and went to the dealership, and GET THIS: Service writer looked at the bulletin, confirmed the code with his buddy next to him, then looked at me and went into detail about how they've been fighting another guys truck with the same code for weeks. They did ECM reprogram, replaced all 6 injectors, cat replacement 2x. Said the code finally stayed cleared after that, but they cant say for sure it's resolved and they just released it less than 24 hours ago with hopes it stays off. Even said they had one of the engineers come out to investigate it, but failed to elaborate on what he did. After all that wonderful news, he tells me they'll just clear the code and it should be fine to drive it for a few weeks, so that other guy can have some time to drive his truck and see if they actually fixed it before they just start throwing parts at my truck too.

 

Uh oh……just shy of 24K and this code shows up today……

 

Sorry to hear… I would not be happy if it was me.

 

I'm at 750 miles and I got the code. Going to the dealer on Tuesday. We'll see how it goes.

 

Dealer got my 21 LM2 last Friday after 2C7A..said they would hang on to it into this week. Called yesterday to come pick it up and continue to drive it as they have to order a part. Code was cleared and no recurrence on 20 mile trip home. Asked if I’d get a speed warning or whatever and they said no. It needs a new SCR2 and it’s not the cat that’s back ordered, it’s the clamps and gasket they’re waiting for. So they’ll let me know when parts come in. On a related note, they apparently performed a radio software update which hopefully will help my iPhone and Apple Car play stay connected. It drops out either through Bluetooth or when hooked up to USB. Got so infuriating that I just hook it up as an AUX through the radio when trying to listen to audiobooks/tunes on trips…NOTE-I DID take the “preliminary report” from above and handed that to them, they looked at it, read the last 3 lines and said “looks like all we can do is the stuff above then just return it to you” THEN they noticed the date of 2019 and said they‘ll hang on to it and a fix was probably found by now….🤔
I’ll keep y’all posted on progress….

 

Looks like I am in the P2C7A party as well.

popped up 4 weeks ago, scanned it cleared it, drove 100 miles and it came back.Scanned it confirmed code, took to dealer. Oh you put bad DeF in… I don’t think so. Yup $250 and it will be gtg. Ok keep me a sample of this bad DeF as I’m sending it to the manufacturer as well as a private lab. Well magically the next day no sample was needed because it turned out to be a bad injector for the SCR. Or not. A few drive cycles later and my little friend was glowing again. This time replace the SCR. Pick it up and we’ll no… dead battery. After 3 hours killing time in the waiting room we had confirmation the battery was dead. Replaced and sent on my way with low fuel indicator on. I fill it up run for a few days and in the back of my head I’m thinking I bet it needs to be below 7/8 full to throw the code. This morning just as I hit 7/8 there it was. So a call to GM to put them on notice and we are back at the dealership dropping off my 2022 AT4 with now 2,100 miles (all started about 1,700).

im kind of kicking myself because I’ve had nothing but Fords for 35 years and very few unexpected tripe’s to the service department. They did buy back a 1999 F250 with a clutch hydraulics issue they couldn’t solve and a 2010 Mustang with a control arm busing that kept going out only in the summer of all things but both were painless and I felt I was treat more than fairly. Hopeful if it comes to that I will have a similar experience.

 

CODE P2C7A

I have a Silverado 1500 crew RST 3.0Duramax.
One month and 1,400 miles in, the CEL came on. Took it to the dealership and got it fixed 4hours of total time from getting in to drive out.
Code P2C7A.
Here is the exact case comment and fix from the service department.
CODE P2C7A RELATED TO NITROGEN OXIDES CATALYTIC CONVERTER 2 EFFICIENCY BELOW THRESHOLD. FOUND THE INTERMEDIATE PIPE EXHAUST CLAMP IS THE CONCERN. LEAKING. PERFORMED EXHAUST PRESSURE TEST AS PER BULLETIN 22-NA-168 FOUND AIR LEAK AT THE "NORMA" CLAMP. CONTACTED TAC. AS PER TAC INSTALLED EXHAUST WRAP ON THE MATING SURFACE AROUND THE PIPE FOR THE CLAMP TO SINCH ON TO CREATE A SEAL. AS PER 21-NA-095BULLETIN. PRESSURE TEST AFTER REPAIR. NO LEAK FOUND. CLEARED ALL TROUBLE CODES. ROAD TESTED THE VEHICLE. THE SYSTEM IS NOW OPERATING AS DESIGNED.

Their test drive was for 5miles, I drove back home for another 35miles without any issue.
Let's hope they had identified the right problem and fixed it. Looks like the "NORMA" clamp is the culprit. It is a cheap component that causes a headache. I thought I will put it out there in case someone needs to check for their CEL for same code/issue.
If I don't update my post, everything is fine.
Hope it works out for everyone. A cheap component on a critical EPA system taking out a fine machine.
It's a shame gm is saving few cents up front for a clamp and making us lose time waiting for a warranty fix.

Other than that, love this truck.

 

CODE P2C7A

I have a Silverado 1500 crew RST 3.0Duramax.
One month and 1,400 miles in, the CEL came on. Took it to the dealership and got it fixed 4hours of total time from getting in to drive out.
Code P2C7A.
Here is the exact case comment and fix from the service department.
CODE P2C7A RELATED TO NITROGEN OXIDES CATALYTIC CONVERTER 2 EFFICIENCY BELOW THRESHOLD. FOUND THE INTERMEDIATE PIPE EXHAUST CLAMP IS THE CONCERN. LEAKING. PERFORMED EXHAUST PRESSURE TEST AS PER BULLETIN 22-NA-168 FOUND AIR LEAK AT THE "NORMA" CLAMP. CONTACTED TAC. AS PER TAC INSTALLED EXHAUST WRAP ON THE MATING SURFACE AROUND THE PIPE FOR THE CLAMP TO SINCH ON TO CREATE A SEAL. AS PER 21-NA-095BULLETIN. PRESSURE TEST AFTER REPAIR. NO LEAK FOUND. CLEARED ALL TROUBLE CODES. ROAD TESTED THE VEHICLE. THE SYSTEM IS NOW OPERATING AS DESIGNED.

This is interesting, just read my whole service ticket and it does state “SCR#2 low efficiency. No air or exhaust leaks found. Ordered SCR 2 and clamp and gasket”

So no leaks found (yet!) but still getting parts and waiting specifically on the clamp, which I‘m assuming is Norma! You’re sure right about what sounds like a poorly designed/functioning clamp….Wacky that they would slap some exhaust wrap on it and button it back up without replacing the clamp….but at least you’re driving it.. I’m old enough to remember when exhaust wrap was from JC Whitney and was a common exhaust repair!

 

Good info to know, it looks like this TSB fix just came out mid last month. Hopefully it solves this issue for everyone.

 

This is from an article by Corvette reviewer/blogger/product advertising

"Technical Assistance Center (TAC)Action Centers are designed to gather early product feedback and provide support for the introduction of new GM models. Dealership service departments are asked to report all vehicle issues that require immediate attention, not just concerns that require technical assistance."

So GM is not fully testing their new products, just push it upon the customers and deal with the issues as they pop up. Nothing wrong with it, except you would hope that service technicians through 1000s of dealerships are competent enough to get the issue correctly identified for a bulletin to be issued. That is why some problems go on forever and create pissed off customer base.

 

Truck has been at the dealer since yesterday. They're saying they found an exhaust leak and I will be getting it back tomorrow. I'm hopeful.

 

Well, got my truck back, but it isn't fixed. While the dealer identified the cause of the CEL, the part to fix it is not in stock and I have to wait. They turned off the CEL and it is holding for now.

Like SaltyReef, my issue is the same thing. Leaking intermediate exhaust pipe. The problem is here:

As you can see, the fit isn't great and the clamp addresses it. Now I just have to wait for them to be available. I saw a video taken by the tech, the leak is very evident.

 

Well, got my truck back, but it isn't fixed. While the dealer identified the cause of the CEL, the part to fix it is not in stock and I have to wait. They turned off the CEL and it is holding for now.

Like SaltyReef, my issue is the same thing. Leaking intermediate exhaust pipe. The problem is here:

View attachment 1107124

As you can see, the fit isn't great and the clamp addresses it. Now I just have to wait for them to be available. I saw a video taken by the tech, the leak is very evident.
[/QUOTE

Well, got my truck back, but it isn't fixed. While the dealer identified the cause of the CEL, the part to fix it is not in stock and I have to wait. They turned off the CEL and it is holding for now.

Like SaltyReef, my issue is the same thing. Leaking intermediate exhaust pipe. The problem is here:

View attachment 1107124

As you can see, the fit isn't great and the clamp addresses it. Now I just have to wait for them to be available. I saw a video taken by the tech, the leak is very evident.

Hi revvr, I'm glad they have identified your issue, I'm still annoyed that an incompetent employee assembled it at an angle and the clamp didn't sinch it properly. I didn't take a picture of mine, but it is at a slight angle too. It's not a clamp malfunction in my opinion. There is no way the clamp could pull and align the pipes if the SCR2 component and the rest of the pipe is already attached to the undercarriage.
It's a half-ass job by the assembly and no quality control. Because of the angle, the seal is not seated, hence the leak. That's why they had to put a wrap on mine to aid the clamp.
With that said, still mind boggling that a piece of gasket and a clamp will take forever to get.
Oh by the way, I'm SaltyReef, I updated my profile and not sure how it will post.
As to my truck, so far the patch is holding. No CEL so far.

 

It's nice that your dealer uses a drive on 4 post lift. Drives me nuts that they use the arm lift that goes on the frame for oil changes, which then damages the wax coating and exposes the bare steel frame to start rusting! I live in a salt belt in the winter.

 

Just checking in…killer picture, I’ll crawl under mine tomorrow and put eyes on the clamp! If mine looks any different I’ll snap a pict myself…Driven mine a couple times this week and the code has not resurfaced from them clearing it, and I’m still waiting for them to let me know when the parts are at the dealership….

 

Hi there, finally got a chance to get under the truck and take a picture of the fix. The black exhaust wrap is doing what they intended to do, albeit a bit ugly, lol. A monkey would have done a better job at applying it. Good luck everyone.

 

Yikes! But I reckon it’s doing the job! Here’s ol Norma under my truck! I wish I could see what the two pipes look like under the clamp, doesn’t look like a regular flared out/slip in joint based on what the clamp looks like..

Two bulbous flares stuck together, or maybe just halves of flares? I guess it’s made to swivel a bit… Mine does seem to look a little straighter overall….?

 

Yeah @SaltyReef that job looks like they could not care less.

@Fordt is there tape under the clamp?

Updating on my truck: Did a 400 mile trip yesterday and I got the CEL again after an aggressive evasive maneuver trying to avoid crashing into someone that was speeding and changing lanes and did not see I was there. Hard braking and swerving apparently made it come loose again. However, CEL went out on its own a few miles later, not sure exactly how that happened but it is still off.

Still waiting for the dealer to get the Norma clamp so that I can fix this for good.

 

No tape under mine, but I‘m waiting on a new cat and clamp according to dealer. And my CEL hasn’t reappeared….hopefully they won’t make matters worse by replacing things!

 

Yes @revvr, after seeing how much they care doing it right, I will not be going to that dealership again. It's sad that we have to see the carelessness first before eliminating them. But I was in a pinch and it got fixed for now.
@Fordt, I'm thinking of ordering some of that tape and a clamp to have it in my toolbox, can't trust those bozos to do it right. Or to have the parts when needed.

Also, the first service is included with the purchase of the truck. It covers the oil and filter change and tire rotation (7,500 miles or 12 months whichever comes first).
Would you guys trust them to do it right at this point? I'm contemplating to forgo the free oil change with all the horror stories (putting regular oil in a diesel engine etc.)and do it myself. Amazon has a deal on OEM AcDelco oil with filter for $79.99. And AmsOil can be ordered online for a bit more.
I will probably change the fuel filter as well at that time and it is not covered.
I personally had multiple issues with other brand dealer service departments. Dodge did a transmission oil change for me and the truck started leaking oil from transmission the next day. Different dodge service, newbie poured windshield wiper fluid in a engine coolant reservoir.
Toyota skipping oil filter change while changing the oil.

I'm keeping this truck for a long time, don't want a chance ot for saving $80, I will waste my day at the service department anyways, might as well crawl underneath. Any thoughts?

 

Yes @revvr, after seeing how much they care doing it right, I will not be going to that dealership again. It's sad that we have to see the carelessness first before eliminating them. But I was in a pinch and it got fixed for now.
@Fordt, I'm thinking of ordering some of that tape and a clamp to have it in my toolbox, can't trust those bozos to do it right. Or to have the parts when needed.

Also, the first service is included with the purchase of the truck. It covers the oil and filter change and tire rotation (7,500 miles or 12 months whichever comes first).
Would you guys trust them to do it right at this point? I'm contemplating to forgo the free oil change with all the horror stories (putting regular oil in a diesel engine etc.)and do it myself. Amazon has a deal on OEM AcDelco oil with filter for $79.99. And AmsOil can be ordered online for a bit more.
I will probably change the fuel filter as well at that time and it is not covered.
I personally had multiple issues with other brand dealer service departments. Dodge did a transmission oil change for me and the truck started leaking oil from transmission the next day. Different dodge service, newbie poured windshield wiper fluid in a engine coolant reservoir.
Toyota skipping oil filter change while changing the oil.

I'm keeping this truck for a long time, don't want a chance ot for saving $80, I will waste my day at the service department anyways, might as well crawl underneath. Any thoughts?

I wouldn't be afraid to let them do it, just insist that their Diesel Tech do it and not the fast lane Jockey. Check the part # on the repair bill for correct oil amount and filter. Check your oil in the lot and make sure its full. Its free and you already paid for it one way or the other.

 

I've heard stories of dealers not changing out filters. You can make a mark on your current filter and check afterwards to see if it is gone. If gone, they changed the filter.

If I had a way of lifting this truck off the ground, I would be doing my own work, including fuel filter and this exhaust clamp. But I don't, so I have to rely on dealer.

CEL is back on for me

 

Sounds like you have a movement in the exhaust system and the CEL is coming back whenever there is a pressure drop due to the leak.

I hear you, I have drive on ramps that will add extra 10" to the truck and will have it at an angle for easy oil drain. I'm using a flat 15qt drain pan and the clearance is more than enough for me even without the ramps.

 

Do you guys have this exhaust clamp condition as well (ie: clamp bottomed out as in figure 24)?

Particulate Matter Sensor Protection Tube Performance Diagnostic Setting False DTC – TechLink

gm-techlink.com

 

I‘m not sure it isn’t supposed to be tightened that tight so as to not leave any slack or space for exhaust leaks??? But reading the text and the repair calling for duct tape is kinda wacky!

 

I’ve done all my own oil changes after the first free one. I either get my Dexos D kit from the ‘Zon or the DMax store. Put a Fumoto oil valve on at the second one and do em every 6K. I’ll do the fuel filter as well, just drive it up on a double stack of 2x12’s for some clearance. The dealer says they have the two good diesel techs that only work on max’s so sometimes the wait is longer….so I guess I trust them at this point. But no calls from them yet on the replacement parts (and I’m not sure I need them!).

 

Thats what it’s basically saying in the Tech link. The clamp bottoms out before applying sufficient clamp load on the joint. Which would then cause the exhaust leaks you guys are seeing…?

 

Hello everyone, just wanted to post an update and see if everyone else has one.

So far so good on my babymax fix. Even though the dealership did a monkey job on applying the tape under the clamp, it is holding up. Close too 400 miles and no emission issue.
Great engineering, poor execution.
And here is the crappy tape fix pic
I'm going to get under the truck and check every bolt and connector. Happy driving the 3.0 Max

 

thanks. Please keep us posted, and we are keeping our fingers crossed for you. Obviously a technician who either does not take much pride in his work, or someone who couldn't reach in well enough to get the tape on cleanly.