When it performs properly, the 2002 Honda Civic's OBD-II computer system smoothly regulates multiple functions such as shift points, engine timing, and air-to-fuel ratios. An error in any of these settings, however, can cause poor performance. Resetting the computer to its factory state will erase any corrupt settings and ensure smooth operation.
To simply turn off a diagnostic light or clear an error code, a reset of the computer is not recommended for this vehicle. Instead, use a code scanner, to preserve all settings except the selected error code.
Open the battery box cover, exposing the connections underneath. Use a socket wrench to loosen the nut securing the black (negative) cable to the battery and remove it, paying careful attention not to let it come into contact with the red (positive) cable.
Hold down the horn button for several seconds to use up the stored energy inside the computer's capacitors. To allow the system time to fully reset, wait at least 10 minutes before continuing.
Reverse the previous steps to reconnect the black battery cable. Start the car and allow it to idle for a few minutes before driving. The engine may run rough at first, but will smooth out as the computer relearns the various settings.
