Goofy Codes? Check your battery.

[TheAgency]

Our 21' 6.2l Yukon Denali, which has been otherwise pretty good, threw itself into limp mode yesterday. A call to OnStar showed p1400 ECM - Engine System, p16f3 ECM - Engine System, and c2a07 ABS - Braking and Stability System. I thought it was strange that both the engine and braking/electronic systems were indicated as faulty.

At 53,000 miles, along with Minnesota weather and the truck having sat for almost a week, I figured starting with a new battery before anything else was a relatively inexpensive bet worth making. From my experience, these ECMs and systems are extremely sensitive.

Sure enough, after leaving the old battery disconnected for almost an hour, the new battery solved all of the issues. Thought I'd share in case anyone else finds themselves here.

 

[Stbentoak]

If you get lots of multiple codes out of the blue that don't make sense, many times it is a connection/grounding issue or next stop, load test the battery. These are simple checks to make before you jump to other conclusions.