Diagnostics manual says this:
I do recall seeing this code pop up for someone else on the forum a while ago. I couldn't begin to tell you what went wrong, but it has something to do with the drive motors providing torque when the engine is running in Neutral (or Nuetral, if you're the person writing the manual...), which obviously should not happen.
Is your car still driveable?
EDIT: The conditions in the manual are pretty confusing even for me, a computer programmer, but it looks like it
may be possible for this code to throw if the car's in Neutral with the engine running for longer than 33 seconds regardless of what the motors are doing.
One possible scenario I can see causing this would be to shift to Neutral while the engine is on (Hold or charge-sustain mode) and then come to a stop, as I don't believe the engine will shut down in Neutral in this case. Did anything of the sort happen...?