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Engine Power Reduced / Unbalanced or underboost turbo error codes

3K views 4 replies 5 participants last post by  williamhearst 
#1 ·
Missing and desperately want her back…

Ok, I know where she is… but I am not sure when I will see her again.

3 weeks ago I got an alert on the dash indicating engine power was reduced due to some issue. I pulled the codes when I got home and it indicated there was a turbo pressure imbalance and underboost.

The local dealer has been less than responsive and I am losing confidence they know what they are doing… I am in Middle Georgia and my dealer options are extremely limited at this point. The dealer doesn’t have or won’t give me a loaner car. I just took on a new job and cover the whole South East US now. I need to hit the road and rental cars are ridiculously expense.

They have told me that they have checked all the vacuum pressures, electrical connections and TSBs applicable to my specific car. They can find nothing wrong with the car.

They are now saying they need to contact GM for added guidance and approval to drop my motor as that is the only way to access turbo chargers. I am absolutely sick to my stomach. I can’t imagine how many things need to be taken apart like the transmission, suspension and other components in the way. I am fearful she will never be put back the same way.

I know the turbo issue has been a problem with early CT6s. I have a 2018 CT6 Premium Luxury 3.0tt. I thought only 16’s and 17’s had issues.

Several questions I have for the group are:

Has anyone with a 2018 had turbo issues?

Has anyone gone through having their motor dropped for this repair?

If so, how did your car turn out after the experience?

Any ideas or experience elevating this situation to Cadillac or GM? Who can I reach out to for escalation?

I have so many questions… probably some I haven’t even thought of, so looking for advice.

I love this group and my car. It puts a smile on my face most times and I felt fortunate not to experience some of the bad things others have mentioned… I will say if this ends poorly, I will never buy a Cadillac or any GM product again. I got superior better service and support from Genesis and Lexus or the years.

Sorry for the long post and I certainly don’t want to sound like a whiner, but I’m pissed off. LOL!
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#4 ·
Engine does not need to to be dropped out to fix a turbo. Likely one turbo failed, the other is fine. But with one turbo down, the pressure from the other one just bleeds across the intake thru the other turbo (that’s not spinning) and you get an under boost code. Simple stuff.
They should pull the intake boots off the turbos and shine a flashlight in there while the engine is running. One will be spinning and one won’t be.
 
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