GMC Sierra AT4 1500 Problems. Hassle Free Fix? Happy 2024!

[@andrealmeida9450]

I own a 2021 GMC Sierra 1500 AT4 3.0L 6L and have experienced all the same issues and more. I just had the transmission replaced two weeks ago and have dealt with multiple problems, including sensor failures, DEF system issues, an intercooler leak, and transmission module codes. My truck has been at the dealership 12 times, each visit lasting 2-3 weeks. I bought it brand new, and now it has 65,000 miles. My next step will be to involve a lawyer to handle this matter.

[@Donslife]

🤯

[@ChrisJones-rl5ow]

Had this code n issue happen to me! Happened on a very cold night, -45 Celsius, fort Mac Alberta, had to bring son to emergency so I started truck and left without any warm up time what so ever, had to do 2 oil changes to flush out fuel in engine. All fuel got into my cats and they basically melted,techs said they never seen cats like it before. had to replace both of those. All 8 spark plugs as well, GM never covered any of it I did all repairs and paid for it myself, jus left cats off being $900 a piece. Was almost a $4000 bill at dealer

[@Donslife]

Ouch

[@randyrollins5969]

I have a 2019 GMC Sierra. I had been with out my truck for total of 6 weeks in all 5 visits to the dealership every time thinking they got the gremlin. They replace my battery and PCM and days later symptoms came back. While my codes are not the same, I had p305 and many others. Sometimes the engine light would come on and auto start or start stop would not work. I feel your pain! They had their best tech on it and he was stumped as well. Then he reached out to GMC tech support for help. I have a lot of the mods that I have learned from your videos, so thank you! Long story short it came down to a fuse that was blown but not blown. The tech said in his 30 years of service he has never seen a fuse do this. The fuse had a factory defect with a hair line fracture that gave up the ghost when it wanted to. This was checked with a multi meter. Sorry for the long comment, I just wanted to express my excitement that they figured it out. I love my truck....Oh make sure they check the fuses!!

[@sirius334251]

Sorry to hear that. I have a ‘19 as well. Had all my brake sensor issues before my first service. I’m now at almost 70,000 km with no further issues. Good luck!

[@Bruce-c3g]

I have a 21 Sierra SLT. 29,000 miles, and so far no problems! Love the new Vette!

[@Donslife]

Thanks for watching! I love the vette too, sadly I lose subscribers every time I post a new video it. 😢 🤷🏻‍♂️

[@ericpoole8452]

I’m bringing my 2024 GMC AT4 3.0 back to the dealership for the second time since I’ve owned it. Check engine light-reduce acceleration. They had it over a week and put close to 100 extra miles on it. the first time and ended up just doing a hard reset. Check engine light came back on with in a week. I’ve owned it right at 2 months. On the way to dealership this morning.

[@AlejandroP1980s]

Get a Toyota tundra instead or Nissan Titan

[@michaelpanacheese604]

It's the cold weather and pressure washing the truck. Use fuel conditioner red bottle I use. Use to happen to my gmc 1500

[@jamorionstanford698]

Mine has been doing the samething.

[@isachar2013]

Mine had the same codes and ... lifter number 6 was collapsed 😢. I rather went with a new engine , cost around 10k , deductible was $4,500

[@ww4575]

I had that happen once a few months ago changed where i got gas and haven’t had a problem since then.

[@scottinak]

"No trouble found!"

[@martech360]

Ignition coil for me

[@JB-TM-2023]

Hey Don so my last update my truck had all the issue you did. I had the fuel injectors all replaced. 2 weeks later same issue happened and now turned out to be spark plugs faulty and bad. My truck was misfiring bad as well positive vibes your way

[@craigquann]

It's going to be the pump or possibly injectors. Just went through this with my 2017. But now I'm going to watch the second video to see if I was right.

[@08ScottyC]

Loose connection somewhere, or bad gas is probably what the dealer will come back with

[@billforrest9002]

I love GMC vehicles especially the GMC Canyon at4x would love to know your thoughts on those! Love all your videos keep up the amazing job 👍

[@Papasgarage1]

Hey Don, I hope they dont do the classic "lets start with this and go from there routine" the ole process of elimination trick.

[@Donslife]

That would be unfortunate

[@MrNoneya011]

MAF Sensor./airbox air flow after listening for the first couple minutes of the video. If not, LIFTERS!

[@daleschmitt2919]

I live in south Louisiana, wipers don't last at all and like yours it does same thing.

[@BG-vq9fd]

I had a trans problem. When I went in for my appointment the code was low voltage on the mid speed sensor but because it was not active they could not do anything. I could be driving down the road and it would down shift to L5 (approx 3000 rpm at 60 mph)and stay there until it decided to change. Stayed in L5 pulling away from stops. It would lurch forward when putting it into forward. After a few attempts the dealer was able read the code while it was active. They decided it needed a trans wiring harness. Made another appointment after they got parts. Warranty repair was over $1200. After a few days it acted up again. This time they decided to replace the mid speed sensor. That seems to fixed it. This caused me a lot of inconvenience but there is not another brand I would buy. 2020 6.2l AT4. Good luck with your issue.

[@Papasgarage1]

Not exactly sure why it threw the code but obviously when you drove it after shutting it off and restarting it it just went through its drive cycle and being whatever happen the first time didn't happen again so it clears itself. My guess is it didn't like that cold start haha.

[@danielsweeney-me7wm]

Good Luck with this. I had my first codes with the Pulsar LT that I installed. When I took the unit off everything went back to normal.

[@Texas_G_Longhorns]

My Pulsar left me stranded twice. Threw out service 4x4, steering column codes and it wouldn't start both of those times after turning off the truck. I threw that damn thing in the trash. Had it on for about 1 1/2 years

[@juniorshallow7468]

I currently have similar issues and it's the O2 sensors for my 2019 gmc yukon denali. Rough idle, multiple misfire, vehicle hesitate when moving from a stop then it will take off if you give to much gas because of the hesitation. I currently have it parked for now till I get new oem O2 sensors. Apparently the oem sensors have program specifications for that vehicle and the one's I have now is aftermarket ones.

[@emmtee227]

I have a 2019 and the hesitation just started. And has had the rough idle for quite awhile. My dealer doesn’t find anything wrong. 🤷🏽‍♀️🤦🏽‍♀️ annoying!

[@YuppieMullets]

Mine has done this a few times, but it seems to only be when I’ve remote started - I’m now running a Range DFM and haven’t had any issues

[@GolfMissouri]

Our 2020 AT4 is showing ( place vehicle in park). It is in park but shows this and a continual chime for 3 min. Restart to hopefully get it to park without this showing up on the dash. Same thing happened to my 2018 Traverse High Country. Any suggestions? No recall as yet>>>

[@Donslife]

I would disconnect the battery for a couple hours. Reconnect and see if it happens again. If it does, I think you may need to record a video of it and consider taking it in for service

[@sirius334251]

Thanks! Love your channel. No idea how I got unsubscribed. Here’s an apology tip. 😊

[@Donslife]

Welcome back! No tip necessary!!

[@NitroBassFishin]

Considering you have a p050d and a p0307 i would say you have a bad #7 injector.

[@johnconley4080]

Hey, Don great videos. I was just wondering what code reader you use at home and do you like it? 👍

[@zombieresponseteam2256]

Injector went bad is what they will tell you, i have a 2022 silverado and at 13000 miles i had the same issue and my injector went bad

[@michaelfenton4878]

I’m guessing lifter failure due to DFM even though you drive in L9. Im only half way through the video so going to watch the rest now.

[@KS-cn4zi]

Agreed, along with possible bent push rod. It is usually cyl # 7 on these engines. Best of luck, I truly hope that is not the same issue I had on 2015 GMC Sierra Denali 6.2L.

[@lyleb1946]

I had the exact same error code on my car and it is not a GM so it is not a brand specific issue. What I did was move the coil from one cylinder to another then when it came back on the other cylinder so I could confirm it was the coil I moved. Then I went ahead and replaced all my coils and spark plugs. Mine is a 4 cylinder Kia but uses the same Denso branded coils and spark plugs the GM will have. All new plugs and coils also improved performance.

[@gasparsperformance9841]

Could be the coil having an issue in the cold weather but starts to act normal once it’s warmed up.

[@mpltl69]

Various things. Cold weather Bad fuel Bad fuel evaporator valve Bad coil Bad plug

[@truraza]

Wire harness!

[@fixitdanner]

I hope they fix it quickly and don't give you the run around.

[@craigquann]

High pressure fuel pump.

[@chadgodfrey4364]

Dealership will say not enough information to diagnose the problem. Coil or injector maybe plugs. But the hesitation on start up you’re not gonna like the answer to that one.

[@2cthetruth]

Maybe you need more lights? Should have gotten the diesel bud!

[@johnwinter9722]

How old is the fuel filter, or is that too obvious/easy? I am knocking on wood, as my '22 Silverado with 56,000 miles on it has been, and remains, flawless in its performance and reliability. Oil, diffs, and transmission service. Period. I have the 5.3, my third, and it has plenty of power, gets reasonable gas mileage, and runs on plain old 87 unleaded.

[@RocketIIITurbo]

My bet is some sort of moisture in the fuel line, perhaps due to weather Or electronic component such as a sensor going a little off due to the cold. Put the truck in your garage & it will be fine. I have a ‘21 Trail Boss 6.2. Borla pipes & Pulsar LT are my biggest mods. Running the Pulsar since 6K miles. Now have 77K miles. No problems. Just scheduled maintenance. Like you say - knock on wood.

[@jerrydausman8128]

My first thought was bad fuel (p0300). How many miles on your truck?

[@markmanning5683]

Hey Don and Wife. It's simple, It is the Winter GOD telling you to become Snow Bird's and buy property in Florida for those winter months and go home in late March. I would love to see the diversity of Videos going back and forth. It's just $$$, you can't take it with you to the next life, Spend It.

[@michaelfenton4878]

Why do you keep suffering through the Canadian winters? So many Canadians have migrated to Phoenix and I work for two of them and know countless others, including my dad. Come to the Valley of the Sun and visit the snow on your terms.

[@Overpar73]

I'm usually told they can't duplicate the problem and charge me a huge service fee!!

[@markmanning5683]

Generous Motors strikes again! Got to keep big bucks for Mary Bara salary and benefits.

[@jonnewton8364]

My guess is has to do with the colder weather.

[@lemmuhj]

Cold weather (i hope)

[@jasonemme5477]

Injectors are bad. Had mine done on my 16 silverado at 45k

[@joet8310]

I think they will say they couldn’t find anything wrong and can’t duplicate the problem

[@Sandkei]

😄 Sounds like you have been there before as well.

[@joet8310]

@@Sandkei not with my 2022 trailboss knock on wood but been there with my 2014 Silverado the dealer couldn’t find the miss fire so I ended up finding it myself it was a bad spark plug wire.

[@Sandkei]

@@joet8310 Mine was a 2015 Colorado service power steering soon warning. I traded it in after a few months of back & forth to the dealership frustration.

[@REBooner30]

First thought was the lifters but sounds like others here have a handle on what’s likely going on.

[@transplantyooper]

What scanner and app are you using?

[@Boobtube.]

listening as well for a answer.

[@Donslife]

amzn.to/48vy91B

[@Donslife]

amzn.to/48vy91B

[@Boobtube.]

@@Donslife thanks! looks like a great unit and for a good price for all that it does.

[@Donslife]

@@Boobtube. It has helped me with so many things including buying used vehicles for my kids. Also helping neighbors and friends diagnose things quickly

[@chadatchley6705]

Cause: It’s too dang cold up there!

[@Synwright]

Been following you since before you got your new GMC AT4. Love your content. Have know I idea what the issue could be. But will be waiting for the notification. Best wishes on the verdict.

[@4961Studebaker]

My first guess is the dealer cop out answer, they will tell you it’s the accessories you’ve added. My first guess or where I’d start with is water in the fuel, or depending on your temperatures maybe some small droplets of water froze in the injector. I don’t know your fuel treatment regiment. (HEET) hope it’s nothing serious. Good mechanic would look at the amperage down to the milliamp at the injector just incase as well.

[@bmaul62deepsea16]

No worries man I am a gm lover lol, but it sounds like the pig tail connectors to the injectors probably due to cold weather, electronics hate the cold!

[@Return2Nothingness]

How much gas was in the tank? Not sure if that could somehow have an adverse impact with the cold temps...but I agree with another poster, they'll probably say they can't replicate/see nothing wrong.

[@Donslife]

7/8 full

[@FastSS02]

@@Donslife is that a Canadian measurement? LOL

[@Donslife]

Fractions are the bomb!

[@Boobtube.]

@@Donslife 7/8 th or 14/16th? LOL

[@Donslife]

@@Boobtube. you’re really hung up on this 😂. I kind of wish I had said 79.625 litres out of a possible 91. Yes litres not liters.

[@DougT25427]

Be thankful for the long run of nearly no trouble out of your AT4 until now. Its just a wild guess but I lean towards injectors being the problem. Overall I believe these auto makers have embraced planned obsolesce and are using software to generate expensive service bay trips. I’ll always be convinced the automakers know how to build mostly trouble free gas or diesel engines. They don’t do it because there is too much money to be made by building cars and trucks that don’t last very long. By the way… I got into a near argument with a service manager who insisted the nearly new Isuzu NPR 6.0 gas chassis I bought DID NOT have a fuel filter. I pushed the argument a little too far not believing for a second a major manufacture would build a vehicle without a fuel filter… but they sure as hell did. Not surprisingly I have since found out injector replacement on these engines is a common service… with little wonder.

[@2cthetruth]

Planned obsolescence could be a factor too. The WEF wants fossil fuel engines to be eliminated by 2030-2050. This is agenda 2030 in action. If you are ignorant of agenda 2030 look into it please as it is most definitely not a conspiracy theory. They will make fossil fuel engines impossible to maintain through crappy design and cost. With a collapsing economy at hand, war is inevitable. Get ready!

[@Boobtube.]

so you were wrong and ate crow. I tend to not push things to far unless I know 100% I am correct, so the other person gets to eat crow. If I do not know 100% about something, I will stay quiet until I do my own research.

[@DougT25427]

@@Boobtube. It is amazing how you totally missed the point of my short "no fuel filter" story. The entire point was 100 out of 100 people would have been wrong to assume a new vehicle would be produced purposely without a fuel filter. The story’s emphasis is shockingly about no means to filter the fuel... not that anyone was wrong. I suggest you research and acquire a new tendency... to resist the urge to make nonsensical comments on KZbin that add no value to the conversation.

[@Boobtube.]

@@DougT25427 ? In the end you were incorrect, were you not? And you got in a heated argument with someone who knew the facts. All of this could of been avoided if you would of did some research beforehand. My point is, which you seem to of not obtained, is that it is best to not argue with someone unless you are 100% sure you are correct. Assuming things should be a certain way just because that makes the most logical sense does not mean that is the way things are. I agree with you that no fuel filter would be crazy and that most would think the same. My point is that you handled it wrongly with the service manager. My comments are only nonsensical to you and add no value to you. You have no way of knowing what information others may obtain from my input. You seem like a "my way or the highway" type of personality person to me.

[@teddbobb4672]

As a former automotive technician, and now automotive instructor here is what my professional opinion is. P0300 Random Multiple Misfire usually happens when it’s just that Random misfire and it was more than once. P0301-P0308 is when it’s a dead misfire on the associated cylinder, meaning the cylinder is misfiring every single time. Usually when this is the case the CEL is flashing. Most probable is the ignition coil, next guess could be an injector issue. The dealership will most likely do nothing because it doesn’t have a current fault, and it’s not actively misfiring. Do you have the electronic AFM/DFM delete? Edge Pulsar LT?

[@caseysathan]

How does the pulsar Lt factor into this? I'm curious about that device

[@Boobtube.]

@@caseysathan Pulsar eliminates AFM/DFM and keeps all 8 cyl firing all times, lessening chance of a lifter failure.

[@Boobtube.]

He just uses L9 on transmission to keep AFM/DFM dead.

[@jeffhurley9291]

Vacuum leak 🤷‍♂️

[@joshraines]

Curious if the stutter start is also because of this. I have to think bad spark plugs.

[@Texas_G_Longhorns]

Sounds like a bad coil(s) pack.

[@krisr7324]

Could be bad fuel, curious what octane you're using. I know it can be very difficult to find 93+ octane in some areas, even in the city. I never run less than 93 personally and go out my way to do so .. I'm meticulous like that 😔

[@Boobtube.]

why would bad fuel only affect cyl 7?

[@krisr7324]

@@Boobtube. I'm not suggesting this is the root cause by any means, perhaps my comment could've been better formulated. Bad fuel can cause issues in these engines period, but I'm not suggesting this is the case. I'm also curious about any fuel additives, I think he's used these in the past.

[@Boobtube.]

@@krisr7324 agreed bad fuel can cause issues. I took your comment as saying that was the cause of Don's problem. Thats the problem with text, no emotion attached.

[@nrxhavoc]

the cuts inbetween words are soooooooooooooooooooooooooooo fucking annoying

[@Donslife]

😂 Then definitely don’t watch my older stuff. Just don’t do it