Received message today 171 miles until speed reduced to 65mph with 5,395 miles on my 2021 GMC Sierra Denali 3.0 Diesel.

E

Eastwood

Member
May 18, 2021
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I drove approximately 10 miles around 65mph after the message came on and the message went out after a few miles on the highway. Got home I now have a yellow engine symbol in the lower right corner of my instrument cluster staying on. When the message came on I couldn't change to the screen that tells you your DEF level in the tank. After the message went out I was able to check my DEF level and I have about 3/4 tank left. Will contact the dealer and advise them to schedule an appointment to have the truck looked at. Today 1/27/22 got my truck in for service. Dealer service said DTC code P10DC and P20BE is what they found which is related to the DEF tank heater. An hour after they had it in the shop the service rep said they'd have to remove the DEF tank to find out why they aren't getting a signal to the DEF tank. Preformed diagnosis and found DEF tank heater module connector was not properly seated. Reseated DEF module connector and cleared the DTCS code. After leaving service center I drove 40 miles and the check engine light stayed off. Hopefully this resolved my problem and time will tell if this was the fix.
 

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It sounds like you've had a sensor go bad considering the check engine light is now on... if you're wondering what the code is, you could get the code from onstar.

Keep up updated what the dealer says.. the last time mine told me I had XXX miles left, I filled up and went on about my way.
 
BoostN said:
It sounds like you've had a sensor go bad considering the check engine light is now on... if you're wondering what the code is, you could get the code from onstar.

Keep up updated what the dealer says.. the last time mine told me I had XXX miles left, I filled up and went on about my way.
Click to expand...
Thanks it will be several weeks before I'm able to get to the dealership but will posted on what they determine is the problem.
 
BoostN said:
It sounds like you've had a sensor go bad considering the check engine light is now on... if you're wondering what the code is, you could get the code from onstar.

Keep up updated what the dealer says.. the last time mine told me I had XXX miles left, I filled up and went on about my way.
Click to expand...
Dealer service said DTC code P10DC and P20BE is what they found which is related to the DEF tank heater. An hour after they had it in the shop the service rep said they'd have to remove the DEF tank to find out why they aren't getting a signal to the DEF tank. Preformed diagnosis and found DEF tank heater module connector was not properly seated. Reseated DEF module connector and cleared the DTCS code. After leaving service center I drove 40 miles and the check engine light stayed off. Hopefully this resolved my problem and time will tell if this was the fix.
 
I just experienced the same warning light @ 10k miles. Took it to the dealer and they found the exhaust back pressure valve was leaking. Hope this isn't an ongoing problem.
 
As a side note, the dealer gave me a new pickup with the 5.3L gasser, only 380 miles. Seemed so sluggish and it wasn't even 4WD. I averaged 17mpg on my normal commute vs 26mpg on my truck. Soooo glad I got this little diesel
 
I am having the same alarms, now with 28,000 miles on the truck. Been in the shop for three weeks now, waiting on a new DEF tank. My dealer, McCluskey, has been good about a loaner.
 
Update: Truck has been in the shop one month now, and dealer says it needs a new DEF tank. Lead time...60 days. I've about had it with the 3.0 diesel, bad news all the way around. If they hold true, whoever heard of a brand new truck being in the shop for 3 months! I've had a case going with GM factory to no avail.
I finally decided I am going to trade this truck in, while it sits in their shop, and buy a gas engine 1500. With diesel being $1.00/gallon more than gas, it makes no sense to own this truck any more anyway. I can't imagine what the bill & frustration would be if the truck were not still under warranty. The long term exposure to expenses erases any potential savings or benefits to running this 3.0 diesel.
 
Good luck with your new truck, in the last week Diesel has been 3.99 at costco in Omaha. Still about .85 more but it is what it is. Only issue I have had so far in 12000 miles is the ECNS but the flash made it go away.
 
Oceandiver said:
I finally decided I am going to trade this truck in, while it sits in their shop, and buy a gas engine 1500.
Click to expand...
Good luck getting any kind of deal, even at MSRP, if you can find one and with all the options you want like heated seats and steering. There is little to no stock, a lot of dealers are asking above MSRP and force people to take their financing and options. It's a brutal time right now to buy any vehicle. Oh, the gassers are having problems with DOD/AFM. No vehicle is perfect.

I know waiting for your truck sucks but it's the story of everybody's lives right now.
 
I waited 8 months for my vehicle to arrive. Anyone ordering now is likely going to be in the same spot. It doesn’t appear lead times have gotten better (I believe it may actually be worse now as there are shortages in other things as well). My truck was built the beginning of Aug 21, just got it last month!

But I hear what Oceandiver is saying, it sucks waiting so long for all this crap. I know first hand... and to top it off having issues with your brand new truck and them not having parts to repair them. That right there should tell you the lay of the land, they are having difficulty getting some of these components.
 
Can anyone explain to me why a DEF tank would have to be replace? I mean it is a tank, like your diesel tan or gas tank, is the tank leaking? Would it be safe to say that the components in the tank cannot be replace? And if they can then why replace the tank, I'm confused!
 
The DEF tanks are heated, so my guess is that the heating element is shot...? Not unheard of. My brother in laws 2020 2500 HD had to have its tank replaced, likely for this same reason.
 
I read where GM stopped selling the 3.0 Duramax due to supplier issues? And they are buying back 2500 Series trucks? I'm just a little fish in a big ocean but damn it seems to be getting rough out there !
 
So let me get this straight, GM can design or build a plastic tank with heaters in it, very sad indeed!
 
GM just announced it is replacing the 3.0 with a new version. I am running away from mine immediately. After 5 weeks in the dealership (truck has 28,000 mile on it), and being told it could be another two months...I have to get rid of this truck. Even if it ran perfectly right now, I don't want to live with the exposure of expense associated with this engine when it is out of warranty. With diesel fuel costing about $1.20 more than gas, the economic aspect of the diesel is wrecked anyway.
Finally, the way I have been treated by GM, it is clear that the $25-$50 billion bailout they recieved (depending on who you believe) just created a woke monster that should have been allowed to go away at the time and replaced by more customer-centric companies.
 
BTW, big shout out to McCluskey Chevrolet in Cincinati. They really did everything possible to help me with getting through the issues with this truck. They find trucks...they dig for them and can deliver, they genuinely don't take NO for an answer. Fortunately I do a lot of driving between New York and the Mid-west, they are actually along the route for me. Check them out if your planning to throw yourself in front of the GM bus. Best Chevy dealer I have ever found.
 
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