2022 Sierra AT4 braking system warnings

grooobz · 2026-08-12T10:34:18-0500

Recently bought this truck and had a service brake pad sensor on for a few days. This morning while driving, I had a bunch of lights come on. Check engine, Service ESC, Service Braking System, Trailer Braking System, Max speed set to 62MPH.

After researching it looked like some people fixed the issue by replacing a low battery. I tested mine and its sitting at 12.43. I took it to AutoZone to have them scan it and the codes they pulled were: C05B0, P25A2, C05B0-00, C116B-64, C116C-13, U0155-00. I have seen other mention ignition coils, misfires and master cylinders. AutoZone's recommended fix was to replace the master cylinder, but wanted to see if anyone had any insight into this, or these codes. I didn't see any recalls for this VIN, but are there any extended warranty notices GM has put out on these that anyone is aware of?

Thanks in advance.

R467X · 2026-08-12T10:46:06-0500

I don't know how much I would rely on the opinion of someone who works at autozone...

It's great that they can read codes. But can they erase them? The first step in such a diagnostic is to run a full scan, then do a clean slate and see what codes remain. But you won't be able to do that unless you invest in a quality scanner that'll likely run you close to $1000.

grooobz · 2026-08-12T11:09:16-0500

R467X said:
I don't know how much I would rely on the opinion of someone who works at autozone...

It's great that they can read codes. But can they erase them? The first step in such a diagnostic is to run a full scan, then do a clean slate and see what codes remain. But you won't be able to do that unless you invest in a quality scanner that'll likely run you close to $1000.

Yeah I agree, I was going to take it to another shop here in a bit with a more expensive scanner. After running it through different AI's they all seem to point to the same issue. Recent brake pad work done and the car was not put into service mode and the battery was not disconnected. But I dont know how much I trust any of that either. We shall see what this other shop says.