check engine/speed sensor

Help! No one can seem to figure out what is wrong with my 96 sentra. My check engine light has been coming on since July. The speed sensor code keeps coming up when they hook it up to the computer. The part has been replaced. But the check engine light keeps coming back on after it has been reset. And they have checked for shorts in the wiring. My speedometer works fine. Does anyone have any idea what this might be? At this point, the only thing they can think to replace is the ECM, but they aren't sure. Any help would greatly be appreciated.
Jackie

We're having the same problem with our 96 Sentra. Did you get yours fixed? Anyone else have any ideas.

Bruce

My 1995 Sentra seems to have problem similar to this, error code was P0500-VSS. It is not fixed yet.

Had the same problem earlier, but check engine light became off automatically after 20-25 days.