The service engine soon light. You especially don’t want to see it come on when you’re on your way to a flight leaving from an airport 3 and a half hours from your house, and when you’re not coming back until 1 in the morning.
Thankfully, the car still works, and I made it home with no problems. I’m tired today, but the wife and son are home now, and everything looks more or less ready to get in order. I even found a mechanic. Now, if I can just get my writing done tonight, I’ll feel pretty good about myself.