Honda Repair: Speedometer, 91 accord, junk yard parts, speedomter

Question
Most of the time the speedomter on my '91 accord does not work and the S light flashes to tell me so.  I understand that the 91 accord has a sort of radio tranmitor for the speedomoter sensor.  Do you think this is the problem? Also, if it is, is it difficult to replace? What about junk yard parts?  Also, after driving my car for roughly 20 mintutes the engine light comes on.  It never used to do this before the speedometer went out.  Are these linked?
thanks for your help


Answer
Yes, the check engine light will come on if the speedo isn't working.  It has a speed sensor located on the back side of the transmission directly below the throttle body.  I would strongly recommend a new one of these sensors as they are pretty common to go bad.  Has just two bolts that hold it on.