I haven't driven the car over a month so I had to jump start it a few times. Don't know if that has anything to do with it but now the tach reads 1,000 rpm too high, and with the engine off, it points to 1,000. Can the tach be adjusted with a scan tool?

 

When you jump started it I trust you ensured you had the jump leads the correct way round, polarity wise! relative to the donor car / battery?

 

Problem stopped after I drove it this afternoon.

 

Good stuff.
Your CEM has probably reset itself.

Sometimes one needs to do that by holding the vehicles + and - battery terminals together whilst being disconnected from the battery approx 15-20 seconds.
Then you reconnect terminals to the battery.