The check engine codes on your Honda are generated by the vehicle's electronic control unit, or ECU. The ECU generates and stores these codes until they are retrieved and cleared from the system. When a code is generated, the check engine light on your dash will light up. These codes normally refer to a problem or maintenance that needs to be done on the vehicle. Before you can fix the problem or do the maintenance, however, you should check the engine codes on your Honda. You'll need a special tool, called an onboard diagnostic or OBD scan tool, which is available from most auto parts stores. The OBD scan tool is the only way to retrieve the check engine codes from the ECU.
Locate the OBD port on the left side of the fuse panel in the passenger compartment. The fuse panel is located on the driver's side of the passenger compartment underneath the steering column.
Plug the OBD scan tool plug into the open OBD port.
Turn the ignition key to the "II" position and wait for the scan tool to retrieve the codes from the vehicle's electronic control unit.
Use your Honda's service manual to translate the numeric codes. Each Honda vehicle has a slightly different set of codes depending on the year and model of the Honda vehicle. Some codes may refer to a specific problem with the vehicle. For example, a code like "P1122" may indicate that the throttle position is higher than expected. However, a code of "P1204" indicates engine misfire, but depending on your Honda vehicle, can refer to a variety of specific problems. If your Honda is equipped with VTEC (variable valve timing), an error code of "P1253" will indicate a problem with the VTEC system. However, you'll need to know which VTEC system your Honda is equipped with and have the specific technical service manual for your Honda to fully decode the error.
