The speedometer in your Honda Civic is connected to a speed sensor in the transmission that calculates vehicle speed from the rotation of the transmission's planetary gear system. This information is sent to the instrument panel and allows you to see how fast the vehicle is moving. Although it is more common for the speed sensor to fail than the speedometer, an electrical short can cause the speedometer to fail. When this happens, you'll need to buy a new speedometer from an authorised Honda parts dealer.
Remove the two screws on the underside of the top of the instrument panel's trim with a cross point screwdriver.
Pull the trim piece off.
Remove the four screws that hold the instrument panel in place with the cross point screwdriver.
Slide the instrument panel forward.
Unplug the electrical connectors from the back of the instrument panel. Since the speedometer is part of the instrument panel, the entire unit must be replaced.
Plug both pinned connectors into the back of the new instrument panel then slide it into the dash.
Secure the instrument panel with the four mounting screws using a cross point screwdriver.
Secure the trim piece to the dash over the instrument panel with the two mounting screws using a cross point screwdriver.