Engine dies at 50%+ throttle

[DuraYuk]

With the messages your getting its most likely something with the DEF system. It thinks your running out or don't have any so it's reducing engine power.

 

[90kpaperweight]

With the messages your getting its most likely something with the DEF system. It thinks your running out or don't have any so it's reducing engine power.

Thanks @DuraYuk I think it is something to do with emissions too. Just to be clear, it does not reduce power. The engine completly dies. It turns off. We have to pull over and restart the engine when it happens.

 

[OR VietVet]

Is it a form of saving the engine from catastrophic failure? I very much doubt it because that could be dangerous in certain types of traffic. The dealer has had it for a month and in all the land, yours is the only one doing this? There should be a TSB about this by now, unless your rig is the first to do this and then you will be the start of a TSB.

 

[DuraYuk]

Thanks @DuraYuk I think it is something to do with emissions too. Just to be clear, it does not reduce power. The engine completly dies. It turns off. We have to pull over and restart the engine when it happens.

Yeah I know what you mean. I'm thinking it sees no def and starts taking away power and it's shutting off. Wonder if it's a software anomaly. If TAC is involved there's really not much more you can do. They have every resource at their disposal. And when I was a tech I never had someone on the TAC line not know what they are doing.

 

[steiny93]

I was a tech I never had someone on the TAC line not know what they are doing

My wife's diesel denali has had a TAC case open since Dec of 2021. I'm supremely unimpressed with their ability to fix anything out of the ordinary.

 

[DuraYuk]

My wife's diesel denali has had a TAC case open since Dec of 2021. I'm supremely unimpressed with their ability to fix anything out of the ordinary.

What about ? You haven't fixed it in 2 years?

 

[90kpaperweight]

Update to this post. Still no diagnosis from the dealership, they nor GMC TAC can figure out the issue. GMC keeps saying they will not do a buyback without a diagnosis. Catch 22.

 

[StephenPT]

Where do you buy your DEF? I'm in-line with DuraYuk here that it seems to be related to emissions de-rating the engine. Turning off the engine at 50% throttle output doesn't sound right though, but there could be a bit more going on.

The DEF tank has a quality sensor and will determine the opacity of the fluid. If it doesn't like what's in the tank, it will de-rate the engine and throw a code. I would first make sure you have clean DEF in the tank.

I really would like to know what made the dealership think to go after the camshaft position sensor. That is a difficult part to remove and if IIRC requires the cab to be removed. Some dealerships were replacing the cam sensor back when there was a crank-no-start issue, which was later resolved via a software update.

Ultimately, it's your rig and you can decide who works on it. I would not leave it at that dealership if they are being incompetent and not making any headway on the issue. I know it usually doesn't help to be a difficult person to deal with, but often the squeaky wheel gets the grease...

 

[90kpaperweight]

Where do you buy your DEF? I'm in-line with DuraYuk here that it seems to be related to emissions de-rating the engine. Turning off the engine at 50% throttle output doesn't sound right though, but there could be a bit more going on.

The DEF tank has a quality sensor and will determine the opacity of the fluid. If it doesn't like what's in the tank, it will de-rate the engine and throw a code. I would first make sure you have clean DEF in the tank.

I really would like to know what made the dealership think to go after the camshaft position sensor. That is a difficult part to remove and if IIRC requires the cab to be removed. Some dealerships were replacing the cam sensor back when there was a crank-no-start issue, which was later resolved via a software update.

Ultimately, it's your rig and you can decide who works on it. I would not leave it at that dealership if they are being incompetent and not making any headway on the issue. I know it usually doesn't help to be a difficult person to deal with, but often the squeaky wheel gets the grease...

Hi @StephenPT I only buy brand name Peak Blue DEF. I heard of others buying cheap WalMart stuff and having issues so I spend the extra $$ to avoid any quality problems. The cam shaft sensor did not sound like something easily replaced. The more they wrench on and take apart the NEW vehicle, the less we want that one back.

 

[StephenPT]

So you have 10K miles on this rig, right? There's another forum member here that had a basically brand new '23 Yukon and received a "Service Emission System" error code - I think within the first 500 miles. No noticeable signs of drivability issues, so he kept going and the code went away. I also lurk on the "Duramax Forum" where there's more activity because it tends to get the crowd that runs this LM2 motor in the pickups and have not seen many, if any, issues come up related to the emission system de-rating the engines. Your issue is the first time I've heard of it shutting down the engine.

If you browse a bit on this forum you'll see there's a handful of other members that have had to deal with buybacks from GM. Overall it seems to work out in the end for everyone, but it's not a pleasant process. I believe all of them up to this point have involved the 5.3 or 6.2 gas engines and their repeated valve train failures. I think a few others had early production '21's that were just lemons out of the factory. If you read through those threads you'll see everyone has to start playing a bit of hardball with their dealer and/or GM support team. Lemon laws vary by state, so you'll need to do some research of your own, but you might be able to find a lemon law lawyer that wants to get involved in your case and it seems once they do, suddenly GM makes your case a priority and it either gets fixed or you get a buyback.

I hope you get resolution soon - take care.