When the "check engine" light appears in your vehicle, it's best to connect your scan tool and find the exact code triggering the problem. Code P0720 identifies the problem as the output speed sensor. The output speed sensor is mounted on the output shaft of the transmission and sends signals to the engine computer, which then controls the speedometer. It's important to replace the faulty component immediately to ensure your speedometer and other components work properly.
Place the vehicle in "Park" on a level surface. Turn the engine off and allow up to an hour for the components to cool.
Raise the front of the vehicle with vehicle jacks. Give yourself enough room to slide underneath the vehicle freely.
Slide under the passenger side of the vehicle and look up. You will see the vehicle transmission. Look towards the front of the transmission; you will see the output speed sensor sticking out on the right side.
Disconnect the wire harness. Pull the wire harness until it is removed. Depending on the model of your vehicle, you may have to push the sides of the harness while removing it.
Remove the bolt that secures the sensor to the transmission case using a wrench. The sensor can now be unscrewed and removed.
Install the replacement output sensor in place and screw into the transmission case. Do not over-tighten. Replace the bolt and tighten. Reconnect the wire harness. The harness will click into place when it's secured. The sensor is now replaced. Slide out from the vehicle and lower the vehicle jacks.