If your abs light is on they would be talking about the wheel speed sensor if its not on and says engine speed sensor is located in the transmission, usually towards the back of the trans near the tailshaft. Depends on trans. manual or automatic, either one would be in your trans. Not a hard fix at all.....one bolt and a little wiggling and it's out! This is a DIY fix! Will not make your car miss, but could have some drivability issues since your car will have to rely on other sensors
and your engine light will usually default your car to a pre-programmed setting....is your speedometer working correctly?