My drive 4 light on my honda accord wagon is

There are two speed sensors. One is on the tranny under the throttle bosy and one is under the tranny.

This is the one under the throttle body

This is the one under the tranny near the right wheel.The Countershaft speed sensor is the best bet. i replaced this one on a 1995 honda accord with flashing d4 and after replacement it was gone.the part will be about 125 bucks.

Your tranny is definately going out, or your speed sensor is bad.