The date on my PCM was lagging one day for months and yesterday all in a sudden it showed the correct day.
Thinking about what could have possibly fixed it.

I'm commuting 50 minutes one way between garages both with no GPS reception. Last weekend, I parked the car outside for >24hours for the first time ever.
Does the PCM sync the clock only at a specific time of the day?

 

Did you cross the International Date Line or break the speed of sound at some point in your travels?
;-)

 

I forgot to mention that my commute is less than 20 miles. That's how we break the speed of sound barrier in L.A.

But seriously: this has been bugging me and now not knowing how it was fixed doesn't make it better.

 

It’s like wanting to know what happened to Jimmy Hoffa. You’ll go crazy if you keep thinking about it. Recommend selling car while date is correct, it adds 5k to re-sale price.

 

I also have a quirky PCM in my ‘06 S.Recently on start it shows a time 6 or 7 hours off. It corrects to correct time within 5 minutes.
No idea what’s going on in the antiquated system

 

Just a guess- 12 hours off (am vs pm) then DST hit????