Sure it was a B code?
P2009 = variable tumble solenoid circuit low
The solenoid is connected to battery power on one side, and the PCM on the other side. It pulls the PCM side to ground to energize the solenoid. When it turns off it monitors for the signal to go high again (since one side is battery and the PCM side should float high).
It turns on the error light when the signal stays low.