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2021 Sierra 1500 AT4 issues

Leslie Politron
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Dc7707 New Member

Dc7707

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Bought new 2021 at4 in December and already had to get it towed back. From what I understand they have defective lifters which caused misfire and bent push rod… apparently they’ve known about the issue. Im considering using lemon law but its sad. I loved the truck but too bad the engine is ******. 

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Dirk13 Enthusiast

Dirk13

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On 6/23/2021 at 11:50 AM, Kanon Morris said:

Ahh, gotcha.  That sort of answers a question I had.  I drove a 2021 elevation 5.3L that did not include the DFM (-$50 on the sticker).  I was curious if the actual hardware was removed, or if that was a software removal.  Sounds like GMC possibly removed the hardware?

I think it is highly highly unlikely gm changed anything at all other than omitting the component they have a shortage of, which is the electrical hardware for control of the system. Those trucks will still have the same hardware in the engine. 

Kanon Morris Enthusiast

Kanon Morris

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8 hours ago, Dirk13 said:

I think it is highly highly unlikely gm changed anything at all other than omitting the component they have a shortage of, which is the electrical hardware for control of the system. Those trucks will still have the same hardware in the engine. 

 

I think you’re right.  I’m still perplexed why this 5.3L 10sp w/ DFM is so much more sluggish than the 5.3L 8sp w/o DFM.  It’s like a night and day difference that me, my wife, and my neighbor all recognize.

 

It’s my understanding DFM only drops cylinders at cruising speed on the highway, and not during takeoff.

 

Any idea why I could be seeing such drastic performance gulfs?

Frustrated Chad Enthusiast

Frustrated Chad

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Truck back in for 5th visit but at my request. I just was not confidante in the truck. 20-40mph experiencing best I can describe is stuttering with acceleration. Only does this when cel is on. After a few days of no driving the cel will turn offand once or twice it would turn off while driving. Then truck would be normal, no issues. 

Anyway I called the service dept stating I'm not confident that the truck won't leave me on the side of the road again. Asked them to get me a loaner until they resolve the issue and truck should be there at the shop until then. 

They had no loaners, so they had to engage enterprise rental car. Driving a 21 white(yuk) Chevy Tahoe with less than 3k miles. First full size loaner the dealership gave me. 

Anyway the rental required approval from GM themselves per my service mgr. So if that's true, I'm hoping the engineers are actually working on the fix. Question is can I trust the vehicle after all this mess. 

 

Oddly my Facebook feed the other day popped up a post from some lemonlarry. Ad meant to look like a post I think. It was listing 19,20,21 sierras and Chevy. Guess they are trying to get a class Action going. Didn't click on it. 

Rhino83 Enthusiast

Rhino83

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Same issue here.  Bought my 21 a month ago with 10 miles on it and last Tuesday got the Diagnostic email, text message and check engine light.  Took pics of all on my phone for confirmation.  Took to local dealer and they hooked it up to the code reader and tripped the p0300 code for random misfire.  Had 1100 miles on it last week.  Check engine light turned off while at dealer but they did not clear it.  Exactly one week later (yesterday), check engine light, email and text reappears with 1254 miles.  Took back to dealer and same code.  I have not noticed any rough idling or driving.  Very frustrating in deed for a $60K truck!!!!

Frustrated Chad Enthusiast

Frustrated Chad

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Truck has been in shop for past 2 weeks. Told them I don't want it back until resolved. They had to rent a vehicle from enterprise for me to drive due to no loaners. Got the call this past Wed that the computer had been updated and I can pickup my pickup... we shall see, I have never heard of engineers getting code done that quickly. Lol fingers crossed. If anything else goes wrong the truck is going back and I'm getting my money back or demand upgrade to the diesel model. Lol

Rhino83 Enthusiast

Rhino83

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Anyone discussing buy back? Any news on any updates? Anyone entertained a buy back? 3 weeks and 3 CELs and 3 p0300 codes with no updates.

Adamace1 Enthusiast

Adamace1

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Posted (edited)

Hopefully they will figuire this out soon. It can be a good motor. I haven't had any problems in my first 15,000 miles. The whole clearing the codes and not fixing anything is a slap across the face for a customer. Gm should be tearing people motors down to find out what the problem is. Or doing a few buybacks replaced with same exact truck and tear them down. Seems like customer service is not to high. I'm talking about all brands. I had trucks from other brands not start when the engine was full temp. Dealers would look at the trucks for hours and say yea it won't start for us also but we can't find out why. Ford wouldn't pay a penny to try to throw some parts to see if it fixed them problem. It was a work truck so I had to leave it running 12 hours a day. So I wouldn't get stranded. And had to fuel up with truck running, because they refused to pay a penny under warranty to replace parts.

Edited by Adamace1
Rhino83 Enthusiast

Rhino83

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Did the ecm update per service bulletin received by dealership last Thursday. No issues as of yet but will see. I have found a few others on Facebook that have done the same.

msween313 Enthusiast

msween313

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15 hours ago, Rhino83 said:

Did the ecm update per service bulletin received by dealership last Thursday. No issues as of yet but will see. I have found a few others on Facebook that have done the same.

They did the same exact thing for me and it took only 2 hours for the check engine light to come on again with the code of P0300.  Took it back to them and of course the light was off at this point and flickering.  The called me back and told me it was bad lifters which GM knows about.  Which I would hope so after reading all these forums.  They told me it could be 6-8 weeks until it can be fixed.  Only has 3,600 miles and this is the 4th time it has been in the shop for issues.  2021 GMC Sierra 1550 AT4 5.3 V8.

Rhino83 Enthusiast

Rhino83

Posted
Posted

Well one week and 2 days after doing the ecm update and the cel is back…guess I’m going back to the dealer for another round.

Rhino83 Enthusiast

Rhino83

Posted
Posted (edited)

Cel was on for 2 days and then off. Drove all last week with no cel but made an appointment to have it checked out again. Dropped it off today and they are looking at replacing the ecm since they updated it last time, but truck is running fine. Still tripping the p0300 code so no changes there. Luckily got a loaner to drive which is a Buick envision lol but at least at not walking. Will update when I get the truck back and let you know what they did.

Edited by Rhino83

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