I have a 20' Chevy LM2 with about 20k miles. Anyone having the same issue? The code I'm getting is P2C7A. First they said a software update would fix it, then it was a bad DEF sensor, and now it's back for a third time. It's under warranty, but I'm losing my time just waiting for them to guess what the problem is.
Dealer cannot fix CEL
3 reading
OffDisturbance
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They're way past "software calibration". That was the very first thing they considered / checked for latest software. We took the truck last week to the original selling dealer (5th time in service in under 1700 miles / less than 7 weeks of ownership) and we are awaiting the buyback process movement.
Will be replacing with another one after the buyback and once one with the specs I want can be built.
'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.
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….
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.
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.
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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.
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.
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!
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At first I was hesitant to let them work on it when the guy mentioned the wrap (they ordered it from NAPA parts and were waiting to be delivered, that part alone was 1.5hours of my 4hour wait time). But he showed the TAC directive from GM and I was like who cares, it's their own protocol under warranty. It's not like I will ever touch that clamp. Or if it goes out after the warranty. It will be subject to replacement anyways. So I didn't have to wait. In your situation, it looks like they are changing the entire SCR2, so the gasket will be torn, and might as well replace the clamp.
One might think with the multiple failures of the same component, they will at least have the part on hand. This appears to be the weak point of the diesel exhaust assembly.
Good luck, and keep us posted. I will do the same.
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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.
"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.
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23 Posts
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:
![Image]()
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.
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.
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.
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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.
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….
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..
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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….?
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….?
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