Code P25A2 on 2021 Yukon - Any ideas?

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arkansasmike

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I just bought a 2021 Yukon Denali with less than 5,000 miles on it. Before I even got it home, alerts started popping up. Steering assist, Service power steering, Trailer brake, Service traction control, Service Esc, etc. See video attached. I took it to Autozone and had them scan it. It showed 2 codes: P25A2 Brake System Control Module Requested MIL Illumination and U0139 Network Communication - Reserved by Document 13. I've taken it to 2 GMC dealers and both have shrugged and said "well it's not doing it anymore, so bring it back to us if it happens again." Well it happened again. 3rd time in less than a week.

I've uploaded a video.

Has this happened to anyone else?

 
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arkansasmike

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Absolutely. Taking it back in tomorrow. Sometimes it seems dealers don’t really want to dive in and find the problem. Posted here in hopes someone else has had the same issue and was able to resolve it.
 

StephenPT

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Multiple systems throwing errors - first make sure battery terminals are TIGHT. If that doesn’t work, then get the battery tested. It could be more complicated than that - but more often than not when you have numerous fault codes it’s a battery problem.
 

Doubeleive

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it's a electrical problem of some type, finding it may be very hard.
take it to the dealer WHEN it is having the problem and request they have there best tech "scope it"
they can use a oscilloscope on it and find the source of the problem, you just have to push them to do it, but on the same token it has to be HAVING the problem happen while they check it. they won't be able to find it if they cannot reproduce the problem, that is how it works, it's like a ghost, you can't find a ghost because you can't see it. hope that makes sense.
mine was extremely rare, it was the alternator making 800ma voltage spike's making the bcm think the key was being turned off/on while driving causing bad handshakes between modules and causing several different codes and errors all at the same time.
what you are seeing in your video is bad handshakes between modules, it could be power or ground, or communication on the high speed lan.
the source of the problem could literally be anything, pinched wire, loose harness pin, bad ground, water intrusion, bad fuse, bad module, bad something.
unless it is something that they find on a tsb from similar reported problems it could take a bit of work to locate the source.

***the whole issue with the dealer here is it has to be doing what it is doing in your video for them to find it and fix it****
there is no magical fairly code that says "hey it's me" because they would have to replace all of them because they are all saying hey it's me, no it's me, etc
then you are just playing whack a mole
 
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Stbentoak

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Maybe you are finding out why someone got rid of it… previous lemon?
Doesn’t necessarily have to be part of a vehicle’s record if bought back….
 
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arkansasmike

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it's a electrical problem of some type, finding it may be very hard.
take it to the dealer WHEN it is having the problem and request they have there best tech "scope it"
they can use a oscilloscope on it and find the source of the problem, you just have to push them to do it, but on the same token it has to be HAVING the problem happen while they check it. they won't be able to find it if they cannot reproduce the problem, that is how it works, it's like a ghost, you can't find a ghost because you can't see it. hope that makes sense.
mine was extremely rare, it was the alternator making 800ma voltage spike's making the bcm think the key was being turned off/on while driving causing bad handshakes between modules and causing several different codes and errors all at the same time.
what you are seeing in your video is bad handshakes between modules, it could be power or ground, or communication on the high speed lan.
the source of the problem could literally be anything, pinched wire, loose harness pin, bad ground, water intrusion, bad fuse, bad module, bad something.
unless it is something that they find on a tsb from similar reported problems it could take a bit of work to locate the source.

***the whole issue with the dealer here is it has to be doing what it is doing in your video for them to find it and fix it****
there is no magical fairly code that says "hey it's me" because they would have to replace all of them because they are all saying hey it's me, no it's me, etc
then you are just playing whack a mole
Thank you. This helps.
 
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arkansasmike

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Maybe you are finding out why someone got rid of it… previous lemon?
Doesn’t necessarily have to be part of a vehicle’s record if bought back….
Yikes. Fortunately the Arkansas lemon law covers used cars as well as long as they mileage is under 20,000. Certainly not what I want, but...
 

Doubeleive

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Yikes. Fortunately the Arkansas lemon law covers used cars as well as long as they mileage is under 20,000. Certainly not what I want, but...
I don't think you have a lemon, you have a electrical problem that once resolved you should be happy with the vehicle
 

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