Check Engine Light...now you see it, now you don't!

[TheOldFartDrummer]

This is in reference to my 2022 Laramie, 4x2, 5.7L Hemi, Crew Cab, 22,158miles: I accidently left the third brake light/bed lights on for a day and a half...came out to find a mostly dead battery. Jumped it with my wife's car, no problem. Later that day, I noticed the "check engine" light had come on. I pulled into my neighborhood Auto Zone for a quick (free) diagnostic. The reader spit out a U1267 code indicating a problem with the Electronic Shift Module (ESM), often triggered after a dead battery. I called the local dealer for a diagnostic appointment. They told me $199 for that, plus whatever repair/replacement parts might be needed. This was all on a Thursday. By Sunday, I noticed the "check engine" light was no longer lit. I contacted the dealer and canceled the appointment. Did I save $199+ or am I just courting trouble?

 

[Dredger]

You likely triggered the CEL with the dead battery. Takes a few drive cycles for the truck to verify it's no longer a problem. Congratulations, you just saved yourself $199

 

[JD Martin]

You definitely triggered it with the dead battery. How do I know? While I was on vacation last week my battery **** the bed. Jumped it off so I could get to Lowe's and brought my portable jumper with me. Drove fine over there, good alternator voltage, no dash lights. Let it run for 30 minutes or so while I got gas and did a couple other things before Lowe's, thinking maybe I left a light on or something. Came out of Lowe's and wouldn't turn again. Jumped it off again, it started, but went almost instantly into limp mode and threw CEL. Drove straight to the parts store and got a new battery (mine was about 7 years old now). Had the guy pull my codes since my reader was back at home. Don't remember the code but it was the same thing, something module from dead battery. Had the code cleared, and drove 650 miles home the next day plus driving the last 4 or 5 days perfectly. Also noticed a little stumble went away.

It's funny with batteries these days. In the old days, you'd see the battery progressively getting worse - headlights a little dimmer, little harder to start. Today everything seems to work fine until one day it's just shot. Happened with my last truck too.