Here's what you should do:
1. Get the code read: The flashing light usually signifies a more serious issue than a steadily lit light. You need to get the diagnostic trouble code (DTC) read from the vehicle's OBD-II system. You can do this a few ways:
* OBD-II scanner: Purchase a relatively inexpensive OBD-II scanner from an auto parts store or online. Many scanners can read and clear codes.
* Auto parts store: Most auto parts stores offer free code reading services.
* Mechanic: A mechanic will diagnose the problem and provide repair options.
2. Interpret the code(s): Once you have the code(s), you can look them up online (many resources exist) or consult a repair manual specific to your 2002 Ford Expedition. This will give you a clue about the potential problem.
3. Address the issue: Based on the code(s), you can decide whether to attempt a repair yourself (if you're mechanically inclined) or take it to a mechanic. Some common causes for a flashing CEL include:
* Misfire: A cylinder misfiring can cause a flashing light. This can be due to faulty spark plugs, wires, ignition coil, or other issues.
* Catalytic converter problems: A failing catalytic converter can trigger a flashing light.
* Oxygen sensor malfunction: A faulty oxygen sensor can affect the air/fuel mixture and cause a flashing light.
* Other sensor issues: Various sensors (MAF, MAP, etc.) can malfunction and trigger the light.
Important: A flashing CEL often indicates a potentially damaging condition. Continuing to drive with a flashing CEL could lead to further engine damage. It's best to address the underlying problem as soon as possible. Ignoring it could lead to costly repairs later on.
