I don’t have the LM2 but have been heavily researching it and have read of others with same issue. I think a few valves have been malfunctioning. Hope you hear something soon. I have heard the part takes a bit to get and GM may be fixing any design issues.

 

Thanks for the info

 

Yes I had the same code this morning a new one is coming next day

 

Same issue with me. I’m a tech and have only fixed one of the 3.0. Of course now mine is the second. I’ve had 3 days

 

Just wanted to say I had the same issue with my truck. Less than 100 miles this issue came up with the fans blowing full blast. I work in the auto body side of things and have my own scan tools. I could see myself that clearly it wasn't overheating even though it thinks it is. I contacted the dealer and at the time they had a mechanic in school for the lm2 duramax and didnt have much experience with it so I monitored it myself. Over the course of a week it popped up 3 different times and each time I cleared it and went about my business. It's now been over 5000 miles and hasn't come back or had any further issues. Maybe it's the valve maybe it's a faulty sensor maybe it's nothing and these trucks are just having a moment. Just wanted to share that mine fixed itself by doing nothing at least for now and that may be an option too.

 

P1098
The Engine and Transmission System is not performing as expected. An issue has been detected in the Engine Cooling System which monitors and controls engine temperature to maintain optimal operating temperatures and avoid overheating conditions. If you are driving under normal operating conditions, please check the temperature gauge on the instrument panel.
If the needle is in the red warning area, the engine is too hot. Pull off the road, stop the vehicle, and turn off the engine as soon as possible.

Service within 7 days

 

I’ve read this post and my truck is showing these same symptoms. Most of the time it’s on startup with a cold engine I will get code p1098 and the fans will be running full force even with the engine cold as ice. I also have a reduced engine power notification. If I clear the code the truck runs fine until the next morning on startup. I did notice some temp fluctuations during acceleration and coasting. My truck usually runs 210 religiously but will now creep to 220 and fall fast. I went to the dealer and they said they would throw parts at it and asked me to fill out a credit app to pay for the cost. Ughhh. My truck has 52000 on it and is a 2021. I know most likely they just want to take me for the financial rollercoaster. I’ve heard and have no proof that the coolant control valve could be covered under the emissions warranty, has anyone heard of this. I’m not trying to sound like a cheap guy but money has just been so tight with this economy.

 

I’ve read this post and my truck is showing these same symptoms. Most of the time it’s on startup with a cold engine I will get code p1098 and the fans will be running full force even with the engine cold as ice. I also have a reduced engine power notification. If I clear the code the truck runs fine until the next morning on startup. I did notice some temp fluctuations during acceleration and coasting. My truck usually runs 210 religiously but will now creep to 220 and fall fast. I went to the dealer and they said they would throw parts at it and asked me to fill out a credit app to pay for the cost. Ughhh. My truck has 52000 on it and is a 2021. I know most likely they just want to take me for the financial rollercoaster. I’ve heard and have no proof that the coolant control valve could be covered under the emissions warranty, has anyone heard of this. I’m not trying to sound like a cheap guy but money has just been so tight with this economy. [/QUOTE Would you happen to have a part number for the control valve? My truck has been down with this issue for weeks and my dealer is telling me there are none available.

 

It has a 100,000 mile warranty on the powertrain.

Maybe your 'service advisor' doesn't deal with 3.0 and 6.6 dmax's?

(2.8's don't have the longer warranty)

 

It has a 100,000 mile warranty on the powertrain.

Maybe your 'service advisor' doesn't deal with 3.0 and 6.6 dmax's?

(2.8's don't have the longer warranty)
I feel that I have the symptoms of a coolant control valve. I spoke to a different service manager today in another town and asked if it was covered and I got a great answer… the system is down call back tomorrow.

 

The UAW strike probably isn’t helping your cause… shortage of parts or not being able to be shipped out.

 

I have 2021 Sierra 1500, 3.0L Duramax. Lately, Engine light was on with message popped up Egine Reduced Power and fan went full blast. I took to dealer, they told me need to replace engine heating/coolant valve and harness but need to order parts because of back order. Parts and labors estimate to fix will cost $5k.
Right now my vehicle is 53k miles, Is still cover under powertrain warranty?

 

I had the same thing happen at the lake on Thursday. Towed boat up fine. Fished a couple of hours. Truck started fine and I loaded the boat on the trailer. Shut truck off to secure the boat and all my gear (about 20 mins). Fired the truck back up and immediately the engine fans go full on, CEL pops up and Service Emisssions/Reduced Power come on in the DIC. Shut it off and tried pulling codes with my iDash. Nothing would come up even with a CEL. Cleared the codes and restarted without issue. Strange things happening with our trucks lately.

 

I’ve read this post and my truck is showing these same symptoms. Most of the time it’s on startup with a cold engine I will get code p1098 and the fans will be running full force even with the engine cold as ice. I also have a reduced engine power notification. If I clear the code the truck runs fine until the next morning on startup. I did notice some temp fluctuations during acceleration and coasting. My truck usually runs 210 religiously but will now creep to 220 and fall fast. I went to the dealer and they said they would throw parts at it and asked me to fill out a credit app to pay for the cost. Ughhh. My truck has 52000 on it and is a 2021. I know most likely they just want to take me for the financial rollercoaster. I’ve heard and have no proof that the coolant control valve could be covered under the emissions warranty, has anyone heard of this. I’m not trying to sound like a cheap guy but money has just been so tight with this economy.

I’ve read this post and my truck is showing these same symptoms. Most of the time it’s on startup with a cold engine I will get code p1098 and the fans will be running full force even with the engine cold as ice. I also have a reduced engine power notification. If I clear the code the truck runs fine until the next morning on startup. I did notice some temp fluctuations during acceleration and coasting. My truck usually runs 210 religiously but will now creep to 220 and fall fast. I went to the dealer and they said they would throw parts at it and asked me to fill out a credit app to pay for the cost. Ughhh. My truck has 52000 on it and is a 2021. I know most likely they just want to take me for the financial rollercoaster. I’ve heard and have no proof that the coolant control valve could be covered under the emissions warranty, has anyone heard of this. I’m not trying to sound like a cheap guy but money has just been so tight with this economy.

hello,
I’m having the safe issue with similar miles I have 44,000 miles on my 2021 1500 gmc elevation with the 3.0 diesel. Did you find an answer for what to do or what is causing this issue on our trucks. I’m in the same boat I don’t want to head to the dealership and pay an arm and a leg for something that can be easy bought or do but if it does come to needing to take it to the dealership I will but I want to do everything I can before taking that route. I don’t know if it matters but I’m from west Texas.

 

I took my truck to Gmc Service last Friday, November 24, service advisor said need to replace Engine Heating/Coolant valve, therefore, it is relate to powertrain warranty. So they will fix for free because my truck still under 100k warranty, also they provided me with brand new truck 2024 GMC Denali to drive until my parts arrive to fix.

 

Are you guys using the block heater before the fans running full blast at startup happens?
Is the temp above 0F when the block heater was plugged in?

There was a bulletin about the block heater / fan thing happening on early 3.0's.
There is a programming update that corrects it.

IIRC, not plugging in above 0F will also correct it if it hasn't had the update.
Once the programming solution was figured out all factory builds since then would have it.


Same article indicated block heater not really needed til below something like -25C/-13F

I didn't check the dates -- it may be that the '21's would have be built after this issue was corrected.

 

Take a look here Coolant Flow Control Valve Actuator Harness Connector Corrosion – TechLink

 

The coolant control valves are going bad on most of the 2021 3L Duramax engines. Mine went out at 54k, brought it to the dealership and it is covered. The problem is there is a nationwide backorder of at least 3 months. I traded mine in for a trail boss with a 5.3L in it. GM knows about this problem and will only consider a "goodwill" incentive after 60 days. I just received a $4,500 incentive to by a new vehicle after I already traded mine in and bought a new vehicle. There should be a recall since it disables the truck.

 

I am in the same boat. 2022 with 56,000 miles. Truck has been at the dealer over 2 weeks now and no ETA on the part. Someone on here rebuilt theirs but GM tech won’t touch it. Has anyone drove their trucks like this and used a code reader to erase the code until their part arrived? Tim

 

Trying erasing the code but engine light was still on

 

I'm in the same boat. Mine is a 2021 3L Duramax Silverdo with 44,000 miles. Started giving Check Engine Light on at 36,000 just past the warranty. Dealership replaced manifold and CEL continued. I think they just wanted to bill the PowerTrain warranty for something instead on the valve. Code P1098 Coolant Control Valve. Dealership didn't want to cover it with PowerTrain warranty. Filed a complaint with GMC, BBB, AG for the state. Nothing yet. Can't use the truck unless unplug negative from battery and plug back every time I'm going to use it. Really bad experience.

 

Yep. I am thinking of getting my truck back and drive it. Part is on order. I am thinking of buying a code reader and erase the code when it comes on until the part is replaced.

 

GM will have a full history of the code being thrown. If you drive it my bet is they won't cover it because you knowingly drove the truck with the defect.
This was GM's response after 60 days. When I received it I told them I'm going to the press. I then finally was given the $4500 towards a new truck:

"We are still experiencing a delay on the part(s) needed to repair your 2021 GMC SIERRA. We understand this is a significant inconvenience and we continue to work diligently to resolve the delay. If further information is made available, you will be contacted by your dealer or myself. Thank you again for your patience and please contact me to discuss any additional questions or concerns you may have.

I can be reached at the number listed below or emailed at CustomerCare@GMC.com (please reply with history to this email for fastest response).

Thank you,

GMC
Phone Number: 1-866-790-5600"

 

I recorded all the codes my truck was throwing from Feb to last month when I took it in. They never said a word about me clearing them and appreciated the extra info to pass on to GM Eng. Many of them came and went on their own, and it never had a "hard" fail until the day I dropped it off. May have helped accelerate the repairs.

 

I just had this service performed at my GM dealership. I had just gone over my 60,000 km/36 month warranty. By about 50 km. I had requested the appointment before going over but I had to wait a week for an opening. They covered it under my extended warranty but charged me a $200 deductible plus tax. Has anybody else had experience with this? Should’ve been covered under the 100 K powertrain warranty? Or was it billed to be correctly?

 

If you went in under the mileage warranty threshold the first time that’s when they should have logged the mileage. Did the stealership do that? Just because they can’t get to it for a week or 2 shouldn't affect the warranty coverage IMO.. I would argue this point with both the dealer and GM.

 

I didn’t physically take it there. I just made the appointment. That was the soonest I could get it to any dealership within 100 km of where I live.

 

They will likely make you pay then unfortunately depending on what the component is if you didn’t stop into a dealer to note the mileage and CEL. What did they replace? It may not have been covered under the powertrain warranty as they are pretty specific on what they cover on the 5 yr/100,000 mile.

 

Replaced the coolant control valve.

 

DId that fix it? You changed the valve and not the sensor right? Assuming those are 2 different things

 

Not sure about that one as it doesn’t list the CCV anywhere specifically so…??