Need some advice - New Yukon AT4 Ultimate check engine light came on

I just purchased a new 2025 Yukon AT4 Ultimate a couple of days ago. Today out of the blue when I started the vehicle the "check engine" symbol appeared in the dash. Needless to say I was not pleased and a little worried. The vehicle is running fine. I wasn't home so I drove it to my next stop. When I got back out to the vehicle the light didn't come on and didn't come on for the rest of the day. I was going to drive it to the dealership first thing in the morning but its literally 2 hours away from me. I can do it, its just an inconvenience but was wondering if anyone had any advice on how I should handle this with the dealer or if I should even bother going if the light doesn't come back on in the morning.

Any advice would be very much appreciated.

First thing to do is get a scanner on it and read the code. It's probably a "stored" code so the scanner will need to be able to read those. If you don't have a scanner check the auto parts store and use theirs to read it.

If it’s new, and your OnStar is active, press the button and have them run a remote diagnostic. It will give you the codes.

WalleyeMikeIII said:

If it’s new, and your OnStar is active, press the button and have them run a remote diagnostic. It will give you the codes.

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Thank you, I will most certainly do that.

WalleyeMikeIII said:

If it’s new, and your OnStar is active, press the button and have them run a remote diagnostic. It will give you the codes.

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The light did not come back on this morning. I called Onstar and the diagnostic report came back clean. With that being said I guess I won't drive down there today and give it the weekend and see how the vehicle behaves. I honestly don't have time to do it today anyway.

Next time the light comes on, get a hold of OnStar and ask them what the code is.

I recommend that you get yourself a quality bi-directional scanner to add to your tool box. Then, you will be able to read ALL trouble codes, along with a brief explanation/pointer to the source of your issue. You will also be able to reset/delete trouble codes, after taking corrective action. You will literally save thousands of dollars in diagnostic and repair costs over the life of your truck, and you will most likely recoup the cost of the scanner within 1 year.

Why would you recommend wasting money on a scan tool for a vehicle with a full warranty left? They won’t be fixing it themselves and what are you going to do with the codes you get anyway? It’s still going to a dealer to get fixed.

iamlegion said:

Why would you recommend wasting money on a scan tool for a vehicle with a full warranty left? They won’t be fixing it themselves and what are you going to do with the codes you get anyway? It’s still going to a dealer to get fixed.

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There are people that chose to be educated on what they own - whether under warranty or not. I personally think its a good idea for someone who's going to do their own maintenance, and as a secondary set of information to have in your pocket if the stealership blows smoke up you rear end about a light that came on and went off.....with no history of it available after a couple key cycles.

Yes, they are pricey, but so are wasted trips to places that can't fix things, or are very good at loading the parts cannon.

iamlegion said:

Why would you recommend wasting money on a scan tool for a vehicle with a full warranty left? They won’t be fixing it themselves and what are you going to do with the codes you get anyway? It’s still going to a dealer to get fixed.

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If your vehicle is under warranty 100% of the time, and if you have no interest in educating yourself in how the truck's operating systems work, and if the local dealer is your trusted friend, then perhaps you don't need to purchase a quality bi-directional scanner.

For me, my truck's never seen a dealer since I purchased it (no longer under warranty, of course), and for those few instances where I need a mechanic's assistance, I go to a local shop with GM certified mechanics, and I pay for their services at a cost substantially lower than the local dealer. And, they don't charge me for any diagnostic services, because before I arrive at their shop, I've already analyzed the trouble codes, and I already know what the root cause of the issue is, using my quality bi-directional scanner.

Different strokes for different folks. You make your choice.