I have just a bit over 3000 miles on my Karma and just got my first MIL. I'd gone to a store and was on my way back; the computer insisted on running the gasoline engine for some reason; and I was going via freeway, so I put the car in SPORT mode for a bit.
Just a bit before exiting the freeway I turned the car back to STEALTH mode but I could see the gasoline engine was still running as the mpg value (on the System Status screen) was dropping. I took the exit and turned left at the light, and some time around that point the engine shut off and the dash chimed and, voila, "check engine" and no more digital speedometer.
Just for experimentation I tried to engage SPORT mode again. No luck: the dials changed color etc., but the engine did not start.
Nothing shows up under System > Diag. I suppose I will have to take the car down to the dealer, which is fine as long as I can make it all the way there on battery power... :s