1. Ensure that your engine is turned off and the ignition key is in the "OFF" position.
2. Locate the self-test connector on your vehicle. It is usually located in the engine compartment, near the battery. The connector is typically black and has a single wire attached to it.
3. Connect a jumper wire to the self-test connector and to the negative terminal of the battery.
4. Turn the ignition key to the "ON" position, but do not start the engine.
5. Observe the check engine light on the instrument panel. It will flash a series of codes, each consisting of a series of flashes followed by a pause.
6. Count the number of flashes in each series and write them down. The first series of flashes represents the first digit of the code, the second series represents the second digit, and so on.
7. Repeat steps 4-6 until all of the codes have been displayed.
8. Once you have recorded all of the codes, refer to the vehicle manufacturer's service manual to look up their meanings and identify any problems with your engine.
