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Vacuum leak and "Exhaust Fluid Quality Poor"

7646 Views 5 Replies 3 Participants Last post by  TERNARYTEACHER
It is about 7500 miles on my Colorado, time for my first free oil change and I noticed a high pitch noise, that increased in pitch as rpms went up, the check engine light came on, the DEF light came on, and the screen read that I would be limited to 65mph in less than 100 miles because of "Exhaust Fluid Quality Poor."

It also had a blown out front driver's side speaker (or at least it sounds blown when there's a lot of bass).

So I took it in to the dealership to have them look at it. They found a vacuum leak around the turbo and are replacing two bolts that will be in tomorrow. (They pointed out that they paid for overnight shipping.)

The guy on the phone said the mechanic thinks that once the vacuum leak is fixed, that all the other problems will go away.

Anyone else have similar problems? All this happened after a long trip 2000+ miles with a camper trailer. I filled up with DEF about a day before these symptoms started occurring.

I will keep people updated. Maybe it will be a problem others will have as well.
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I have 15k miles on mine and have had no problems thankfully. I have towed less than 2k lbs several times so far with no problems at all.
Hopefully it's not a common problem. No word from the dealership today, so I imagine it's not all fixed by fixing the vacuum leak.
depending on where you got your def, it could have gone bad. def does have a shelf life and can go bad over a relatively short period of time (6months for most if im not mistaken). also, 7500 miles is a little long in my opinion when the truck is that new. they recomend 7500 but i would do every 6k for the first 4 oil changes, just my opinion on that. another thing to think about just for future reference, you shouldnt put any def in your tank until the other tank is pretty much burned out. mixing it could result in old def mixing with new def and lowering the overall quality of the fluid
Oil change timing:

I'm just following the oil life meter on the oil change. I understand its not a perfect way to know when to change it, but after working in the oil change industry, I don't find these conversations helpful. If you want to have that specific conversation, do it on another thread, because it is helpful for others on this forum to keep threads on one topic only.

DEF quality:

When you read below you will see it wasn't about DEF. But are you indicating that there is bad DEF out there or that DEF gets old after time? It happens to be that for the two only times that I have filled the DEF tank that it was completely empty first. But doing that purposely would only make sense if DEF is often bad or if DEF goes bad quickly enough for that to be a concern. Are your comments based on experience of DEF going bad in the past? Or is this just a strategy to avoid problems yet to be experienced?

Back to this concern of this thread:

Turns out it wasn't a "vacuum" leak, but an exhaust leak.

Here is the wording from the service ticket "Found exhaust leak from converter to turbo connection. Upon inspection found studs for flange missing. Removed catalytic converter and installed new studs, nuts and gasket..."

So basically they didn't install something correctly to begin with.

The exhaust leak caused the sensor that reports def quality to go out of acceptable range. So once the exhaust leak was fixed, all the other issues were not present any longer.

I just picked it up and don't know exactly which studs were missing, but I will go back and have them show me specifically. Will upload pictures to let others know what to look for in case your Colorado is doing the same thing. But it could just be that this is an isolated thing with my truck only.

I had what I thought was a blown speaker, but the solution was for them to insulate the door panel per TSP DOC#4446912. This is common enough of a problem with all Colorados, so if you notice the same thing, go get yours fixed for free.
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as far as doing this in a different thread, I was just trying to help. im not a pro on how they work, or what to do with them, but I do know enough to be dangerous with a wrench and an impact lol

DEF does go bad over time, its a pretty good shelf life so I wouldn't worry about it going bad in the tank, but if its at a low volume truck stop, I would hesitate to pick up a dusty bottle of it.
I've never purchased bad DEF so its not from experience, however, I would definitely use it as a strategy to avoid future problems.

if it was a vacuum leak, it could be all sorts of different problems that caused it to read bad. it could be bad or it just could have misread. I wouldn't just completely wright off the possibility of the DEF being bad, although it wasn't the source of this particular issue.

if you had a fuel mileage issue during this time or the up until this point, it could also be blamed on this issue. if there was a vacuum leak, it would be hard to get the optimal temp throughout the exhaust which would make it hard to do a proper regen.
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