Running Lean Bank 1 & 2

[JohnZ71]

Hey I have a 2020 gmc 1500 at4 with 29,000 miles on it. About 5 weeks ago I got a check engine light that cleared on its own but yesterday it came back so I was able to take it to the dealer ship. They said it was codes for running lean on Bank 1 & 2. I don't have the code #s. They tried blaming my air filter being dirty but running leans means it's getting to much air. I have an S&B intake that has about 22,000 miles on it that has been on the truck for 14 months with no issues. I'm kind of lost. Possibly a small vacuum leak? Or dirty MAF sensor? Let me know if anyone has had these issues. They said they recommended putting the factory intake back on and see what happens. Truck never felt like it missed a beat. No rough idle or power loss. My MPG has been lower ~15 mpg but I live in ohio so the Temps havnt been to friendly. I do hear a slight "hiss" on the right side of the intake manifold but it's very slight and I can't seem to find exactly what it is.

[Supreme Pizza]

I'm sure you will get plenty of replies on your post.

 

I would wait until the engine is 100% cold.

Then I would start it and then spay starting fluid directly onto the suspected vacuum leak areas. If it revs, then you found the leak.

 

You could also clean the MAF with a can of cleaner from the parts store.

 

Maybe clean the throttle body plate with a can of TB cleaner and a couple rags or toothbrush.

 

I would install the stock intake regardless of any problems.

 

 

 

Getting the exact codes would help.

 

Any auto parts store will read the codes for you, for free.

 

 

 

 

 

Edited January 15, 2022 by Supreme Pizza

[Transient]

It would be helpful to have the codes.  It would tell us more.  Based on my very limited experience, I don't think it's the CAI.  Iirc, it would say something else other than running lean.  The computer would compensate to ensure the AFR runs stoich.  If the MAF was bad there'd be a code for that.  If air was getting in through a tear or crack in the intake tube there'd be a code for unregistered air getting in because it wasn't measured at the MAF.  I wonder if there's something wrong with the fuel delivery.  Maybe an obstruction in the lines from dirty fuel???  I really don't know.  I'm just guessing.  It's really hard to diagnose a vehicle over a message forum and lack of info.  As I said, it's all a guess. 

[KARNUT]

16 hours ago, JohnZ71 said:

Hey I have a 2020 gmc 1500 at4 with 29,000 miles on it. About 5 weeks ago I got a check engine light that cleared on its own but yesterday it came back so I was able to take it to the dealer ship. They said it was codes for running lean on Bank 1 & 2. I don't have the code #s. They tried blaming my air filter being dirty but running leans means it's getting to much air. I have an S&B intake that has about 22,000 miles on it that has been on the truck for 14 months with no issues. I'm kind of lost. Possibly a small vacuum leak? Or dirty MAF sensor? Let me know if anyone has had these issues. They said they recommended putting the factory intake back on and see what happens. Truck never felt like it missed a beat. No rough idle or power loss. My MPG has been lower ~15 mpg but I live in ohio so the Temps havnt been to friendly. I do hear a slight "hiss" on the right side of the intake manifold but it's very slight and I can't seem to find exactly what it is.

It’s under warranty. Put it back stock, I know it’s BS. You have to play their games. There’s more to go wrong with these engines you don’t want to pay out of pocket. Your right about the dirty air filter. It doesn’t matter they hold the cards. 

[max07]

I have had the same issue. The first time the check engine light came on the dealership plugged in and said there were no codes. They cleared the check light and said to come back if it happens again. The second time I checked it myself before bringing it in, showed P-0174 lean bank 2. Both times it happened i was driving in really deep snow. The shop foreman told me it could be a dirty filter. I bought a new filter, so I guess we will see. I also noticed a big puddle of ice down in the bottom of the intake.  Could snow be causing this issue?

[Black02Silverado]

I know not 100% related but maybe your source of fuel?  I get the lean code when I mix E85 higher than a 50/50 mix with 93.  Maybe the place that you filled up put ethanol in the wrong tank?  Just a thought.

 

I wish it wasn't so expensive to convert over to flex fuel on these new trucks.  Only cost me $100  to do my 2016 Suburban. If I want to convert my 2019 it is going to be $1,800.