Turbo Overboost Code

NEVADADSL

NEVADADSL

Member
Aug 17, 2021
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So my 2021 GMC Sierra 1500 LM2 jusst thew a check engine light. Took it to dealer and was told "turbo overboost code". Can't even have it looked at for a month they are so busy which sucks because the wife and I had a trip planned to pull our trailer to Glacier National Park in about 3 weeks. Not happy.
Dealer also stated they had not ever seen this code before. Anyone ever have this?
 
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NEVADADSL said:
So my 2021 GMC Sierra 1500 LM2 jusst thew a check engine light. Took it to dealer and was told "turbo overboost code". Can't even have it looked at for a month they are so busy which sucks because the wife and I had a trip planned to pull our trailer to Glacier National Park in about 3 weeks. Not happy.
Dealer also stated they had not ever seen this code before. Anyone ever have this?
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So did they clear the code? If'n so, has it returned? When it lit up the CEL, did the truck run fine?

If CEL didn't immediately come back on, I would do a few full throttle pulls and see if it comes back. If'n not, I wouldn't give up the chance of getting to see GNP.
 
gemarsh: Yes, they cleared the code and it has not returned. I did a few hard accelerations and so far so good. It has been a couple of days so far and I have been driving it every chance I get and again, so far so good. Truck never faltered with the CEL lit and still runs great. Gonna drive it for a couple of weeks and if it doesn't trigger again I think the trip will be a go. As I stated above I also have a local 3 night camping trip planned late next week and that will be over an 8000' plus pass with the trailer. I figure if it is going to trip it would be then. (Although the original CEL came on just drivig around town...) If all goes well the next decision will be do I keep my dealer appointment? Hoping it was just an anomaly.
 
I'd still take it to them. It's on their dime and it was documented it had the CEL. That way, if something were to happen later, they can't turn around and say " you didn't bring it back".
 
Well I got an appointment in 2 days time at a dealer in Placerville, CA which is 2 hours from me. we willl see what they find out...
 
Yesterday I went and talked to the service writer who I originally spoke to at my local dealer and he assured me that the code would still be in the computer, so this morning my wife and I took separate cars and drove 2 hours for the dealer appointment in Placerville, CA. Since we had driven so far the service writer said he would get the truck to a tech right away on the very slim possibility that I would not have to leave it. Well guess what? There was no code in the computer. The bastards at my local dealer erased it and then lied to my face. The writer at Placerville said to go have lunch, and after an hour or so called me. He had called GM and there was no known issue with this code and the LM2. Furthermore, if that code pops up the truck is supposted to go into limp mode, which obviously mine did not. He also had the tech check the turbo bolts, actuator bolts, checked the turbo for leaks, etc. All was good. Drove 2 hours back home and truck ran flawlessly. So as of now, all is well, and Glacier is back on. Bottom line, Michael Hohl GMC in Carson City, NV sucks, and kudos to Thompson GMC in Placerville CA. They know what customer service is all about!
 
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NEVADADSL said:
Yesterday I went and talked to the service writer who I originally spoke to at my local dealer and he assured me that the code would still be in the computer, so this morning my wife and I took separate cars and drove 2 hours for the dealer appointment in Placerville, CA. Since we had driven so far the service writer said he would get the truck to a tech right away on the very slim possibility that I would not have to leave it. Well guess what? There was no code in the computer. The bastards at my local dealer erased it and then lied to my face. The writer at Placerville said to go have lunch, and after an hour or so called me. He had called GM and there was no known issue with this code and the LM2. Furthermore, if that code pops up the truck is supposted to go into limp mode, which obviously mine did not. He also had the tech check the turbo bolts, actuator bolts, checked the turbo for leaks, etc. All was good. Drove 2 hours back home and truck ran flawlessly. So as of now, all is well, and Glacier is back on. Bottom line, Michael Hohl GMC in Carson City, NV sucks, and kudos to Thompson GMC in Placerville CA. They know what customer service is all about!
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First, service writers are usually just that, then do not necassarily know the technical aspects of these vehicles, otherwise they would be in the shop fixing them. Secondly, in all likelihood, you probably had a momentary overboost signal thet may not have been caused by an actual overboost. These are rolling computers that can and do get wierd signal inductions that set weird codes. I would say just keep an eye on it.
 
jjs34748 I know that service writers are just that: service writers. But to lie to my face is unethical and just plain bad business. If he wasn't sure he should have said so and then checked with his tech. Also I was told that to throw this code the overboost has to happpen twice - but of course that came from the same service writer. And, yes, I will just be keeping an eye on it...
 
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Update I ust returned last night from a 2650 mile trip to Glacier NP. The truck was flawless - no code - and I got 15.1 MPG pulling my 22' Rockwood Mini Lite trailer. I love this truck. I DID use a fair amount of DEF, however!
 
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