exhaust smell in cab '21 denali

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DuraYuk

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I don't think you guys are understanding the course of events.

Issue 1: When the engine was running, exhaust smell happening in the cabin. If you got outside and opened the hood you could very clearly smell untreated diesel exhaust (not regen small). This was diagnosed as a leaking turbo via GM's smoke test procedure. (This exhaust was being sucked through the cabin air filter into the cabin)

Issue 2: After the turbo was replaced; continued to get an exhaust smell at startup (only in the cabin; for say 1 min). Tested the system for leaks, none found. They pulled the cabin air filter, it was stinky (from the previous untreated exhaust going through it). Filter changed, it doesn't smell now.

Issue 3: Check engine light, emissions, ect, sensor on turbo failed. They replaced the sensor and now those messages are gone.



A cabin air filter cannot be the root cause of an exhaust smell within the cabin. Changing a cabin filter will not fix an exhaust smell issue. Their has to be a leak in the exhaust system to get an exhaust smell into the cabin. (I'm not taking about regen smell, I'm taking untreated diesel exhaust smell)
If you are leaking exhaust into the engine bay you will have codes and live data to go with it. Its not unheard of for techs to make up steps in the diagnostic process to make a quicker repair.

As a tech i could tell you anything to validate why I did what i did. They also have to write that in their story that gets turned into warranty.

I'm glad you got ot fixed but something is missing from your story. And it may not be up to you to know as you only know what they told you.

The chain of events doesn't make sense to me. If your getting smoke coming out of a turbo there will be more happening then just a smell.

The fact that you actually got codes later that was blamed on a sensor corroborated a leak being introduced after the fact.

Like i said earlier no way to definitively know since we were not there but as someone experienced in the business and fixing comebacks from techs it is what it is.

If your happy and the car is well thats the end of the story.
 
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steiny93

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It absolutely makes sense as it brings in outside air. Could be any vehicle that contaminates it.
So your saving that GM cabin filters are special and are being contaminated by other vehicles exhaust? Imagine how concentrated the outside air with exhaust would need to be, that doesn't make sense.
 
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steiny93

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If you are leaking exhaust into the engine bay you will have codes and live data to go with it.
This part is where your logic is wrong.

Leaks can occur in the exhaust system without a code or impact to live data that will be enough out of range to flag. Here is an example of one for the diesel that is active right now: https://gm-techlink.com/?p=14365 which incidentally this denali had repaired a few months ago (same deal no check engine light or pending codes).
 

DuraYuk

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So your saving that GM cabin filters are special and are being contaminated by other vehicles exhaust? Imagine how concentrated the outside air with exhaust would need to be, that doesn't make sense.
I'm saying anything could contaminate it. Anything. The exhaust from others. The smells of regen. It is to filter incoming cabin air. Not really rocket science.
 

DuraYuk

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This part is where your logic is wrong.

Leaks can occur in the exhaust system without a code or impact to live data that will be enough out of range to flag. Here is an example of one for the diesel that is active right now: https://gm-techlink.com/?p=14365 which incidentally this denali had repaired a few months ago (same deal no check engine light or pending codes).
You underestimate the sensitivity of emmisions controls and air fuel ratio sensors. Live data can tell you everything you need to know. I promise the computer on a modern car will tell you there's a problem before your nose does.

Right. So they replaced your turbo rather then the valve on the first go around ? You see what im saying ? I stated the turbo was misdiagnosed. The valve was introduced later as your own story lays out. Along with all the emmisions codes that followed as a result.

Dealer will most def get a charge back on that turbo unless the tech went to a creative writing class and submitted a solid story with diagnostic steps to go with it.

I stand by my logic as i have been on the TAC side to help fix things right the first time and was a tech long before that.

There's no skin off your nose. I just hate to see people keep going back and forth to these incompetent service centers and souring their ownership experience.

Many people here are really at the mercy of their service department and lots of issues are just attributed to misdiagnosis.

Waiting on parts forever only for it to not be the fix.

I don't even understand why they let your truck leave for it to break back down shortly after your drive it. Your supposed to drive it to make sure it's fixed not wait for it to come back. Which again points to a misdiagnosis.

I'll leave it at that. At least you have a new turbo :)
 

MoonTruck

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Would like your guys take since I can’t find a post with an answer. If there is and you guys could link that would be great.

I’m getting a smell of what I think is Regen inside the cabin when the vehicle is stationary, like a stop light. Smells like something burning or a “hot” smell. Smell disappears after movement in less than a minute.

I’ve noticed it on 3 separate occasions. I don’t think it’s a regular leak since it doesn’t happen all the time. I keep my AC on auto.

Is this smell normal? I don’t mind it too much but I think my wife is not going to be happy the first time she smells it. It is an unpleasant smell to deal with.

300 Miles on odometer and plenty of highway, last trip of 50+ miles averaged 30MPG.

Thanks for any feedback!
 

Holy Roller

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Would like your guys take since I can’t find a post with an answer. If there is and you guys could link that would be great.

I’m getting a smell of what I think is Regen inside the cabin when the vehicle is stationary, like a stop light. Smells like something burning or a “hot” smell. Smell disappears after movement in less than a minute.

I’ve noticed it on 3 separate occasions. I don’t think it’s a regular leak since it doesn’t happen all the time. I keep my AC on auto.

Is this smell normal? I don’t mind it too much but I think my wife is not going to be happy the first time she smells it. It is an unpleasant smell to deal with.

300 Miles on odometer and plenty of highway, last trip of 50+ miles averaged 30MPG.

Thanks for any feedback!
This is what a regen smells like on a new engine. It’s a hot wax or new furnace odour. This smell is the assembly lubes burning off the engine and associated parts. 100% normal. Likely will never smell again after another month or two.
 
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MoonTruck

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This is what a regen smells like on a new engine. It’s a hot wax or new furnace odour. This smell is the assembly lubes burning off the engine and associated parts. 100% normal. Likely will never smell again after another month or two.
Awesome, thanks for the info. Happy to hear it’s a normal smell.
 

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