My car has been performing well since I bought it in March, save for needing to get the 110 volt charger replaced last month (which I don't consider a car problem per se, but rather a charger problem). Fast forward to this morning, the CHECK ENGINE light is now on. We noticed it about a mile away after we had just left the house. So we turned around an immediately came back to the house.
I had OnStar run diagnostics and the error codes that are thrown are as follows:
P1E00 - electronic propulsion system not behaving as expected
P1EBD - battery charger control not behaving as expected
The first error code has been experienced in here in the forums.
The second error code doesn't even show up here in the forums.
The recommendation from OnStar for both of these codes is to have the vehicle serviced "at your convenience." The recommendation makes the codes sound relatively benign, but the description of the errors, especially the first one reads to me as get this car to the dealer *tonight*.
From outward appearances, the car itself seems to be running fine, but like I say we did immediately turn around to bring the Volt back home, and used our other car rather than driving around with the Volt check engine light on.