Checking the engine codes in a Ford Expedition is made simple using standard OBD-II testing codes and an OBD-II tester. If you don't have a tester, most parts stores will run an OBD-II diagnostic test for you for free. Not only does the tester show potential engine problems, it also shows a vast array of other issues that you may not have even known existed. The OBD-II tester plugs into your onboard computer, diagnoses any potential problems and then displays a read-out of codes that help you to troubleshoot the issue.
Turn your car off.
Plug the OBD-II tester into the OBD-II port located under the instrument panel. The actual port is located between the steering column and the center console.
Turn your car on.
Turn the car off once the OBD-II scanner has completed its diagnostic testing. Most OBD-II tests beep when they have finished.
Write down the codes that the tester shows when it has completed the scan. Use the left or right arrow keys to view additional problem codes if they exist. Write those down as well.
Find the trouble code online for an explanation of its meaning (see Resources).
