Brand new Sierra - Codes P25A2 - U0101/100/146

erotman · August 31, 2020

SIERRA SLT 2020 with 300 miles, Check engine went on and shutoff after 1 min. took it to the dealer and they told me the car fix it self . 800 miles light came back again, took it to autozone but the guy erased the code before reading it :( . got my self a test tool today, light is off, but I can read the same codes : U0146, U0100, U0101, and P25A2.

Mcropper514 · September 1, 2020

Had the same problem with my new 2020. Check Engine line came on the day I bought it with 46 miles on the odometer. They just released a software update for the brake control module. I had them reflash mine last monday and it has been good since then.

Edited September 1, 2020 by Mcropper514

Greyhound6.2 · September 2, 2020

mine came on last week when I was on vacation in Moab the Oreilleys code reader said the P25A2 code was requested by the brake controller the tool would not reset the light but it went away after the next engine start or 2. Taking it to the dealer next week for an oil change and to look in to the mystery light.

LongTrekker · September 3, 2020

On 8/22/2020 at 11:50 AM, LongTrekker said:

708 miles on my new Single cab 4x4 5.3. love the damn truck but DAMN does it piss me off. no brakes and tons of codes after start up. Cleared and came back within 3 cycles. Appointment Monday AM. Code c05b0, p25a2, u0146

#20-NA-155 was flashed in and so far nothing in 100 miles. Will keep this thread updated if anything does.

Parrish Mooneyham · September 4, 2020

Ok gentlemen,

SO sorry for the delay, my apologies as this is going on a couple of weeks now. BUT, once this was verified that this WAS a result of bad programming, I was also made aware of that cylinder #8 failed leak down test and had to be replaced.. ON TOP OF THAT, i kept telling the dealership there is something wrong with the radio and that way it handles the USB Music and Playlist.. Basically, when playing from a Playlist (mind you this is a NON HD-Radio but still the 8" screen), and you stop the truck, leave vehicle, let vehicle fully shut down, re-enter vehicle and start it up. The music will not play and the playlist filename is found but it doesn't show any of the songs in the list. I thought "OH H#LL NO!! NOT AGAIN WITH ALL THE ISSUES!!!". SO, I verified this was a true programming/radio issue as I have since traded that double cab in for a crew cab with more upgraded options on it that I wanted from the beginning.. In this new gray (steel color) truck, the playlist plays just fine even after turning off and back on the truck. Acts like you would expect it to. To start playing where it left off and has NO issued with re-loading or keeping the playlist loaded.

SO YES!!!, I traded that truck in for a new(er) one due to all the issues encountered above. Although, I didn't realize it but it was another Loaner Special, but I don't care as long as the truck runs like it is supposed to. ;). Good luck to all who having to keep their trucks and I truly mean that. This truck will be my last and I'll deal with any issues that arise from here on out unless someone else does something stupid like total my truck ;)..

Madmyx · November 14, 2020

What we all

have to

understand about GMC SIERRA is that it’s much more electronically demanding the your regular Chevrolet. The moment you open a door there’s probably 20

processes going on with your electronics that drain your battery quickly. In all my Sierras listening to the stereo in acc mode was unheard of because within 4-5 mins your battery low warning comes on.
unfortunately there’s no peripheral electronics by pass switch for these instances. But the ultimate fix to that is, dual battery with isolator

my 19 AT4 is no different. But dual batts are in its future.

Shadeekins · December 31, 2022

I had the P25A2 code on my 2020 1500 Chevrolet Silverado, Dealership updated software. Check engine light on. I've got a high end OBD2 meter that can also be used on transports. Had to boost the truck because an air compressor was left on and drained the battery. Plus weather here and rain. Code P25A2 came back and check engine light is back on. Ran the diagnosis on the OBD2 and everything on said truck was tested within spec. Erased code but the check engine light is still on even after driving an hour? Will I have to return to the dealership?

Shadeekins · December 31, 2022

Update, My Ancel HD3300 HD DPF Master Found the code P25A2 and I erased it. than P0130 02 Sensor circuit bank 1 came up. Again ran the self test and everything was within specs. The tester than prompted me to shut down the truck and restart. Check engine light was now off. This all started because I left an air compressor on all night.

Edited December 31, 2022 by Shadeekins
spelling error