* OBD-II Scanner: This is the best option. You can buy a relatively inexpensive OBD-II scanner at most auto parts stores. These scanners plug into a port under your dashboard (usually near the steering column) and will read the codes stored by your car's computer. The codes will be a series of numbers (e.g., P0171, P0420). You can then look up the meaning of these codes online (many websites and forums dedicated to car repair explain these codes).
* Auto Parts Store: Many auto parts stores (like AutoZone, Advance Auto Parts, etc.) will read the codes for free. They'll usually print out a list of possible causes, but keep in mind this is just a starting point. They may also try to sell you parts, so be prepared to say no if you're not comfortable with their diagnosis.
* Mechanic: A qualified mechanic will have the best tools and expertise to diagnose the problem. This is the most expensive option, but it will often lead to the fastest and most accurate solution.
Once you have the DTCs:
1. Write them down: Don't rely on memory!
2. Search online: Search for the codes specifically for a 2005 Ford Freestar. This will give you the most relevant results. Forums like Ford-trucks.com are good places to start.
3. Consider the symptoms: Are there any other symptoms besides the check engine light? (e.g., rough running, loss of power, strange noises, etc.) This will help narrow down the possibilities.
Important Note: Driving with a check engine light on can potentially cause further damage to your engine. While it might not be a catastrophic immediate failure, it's best to address the issue as soon as possible.
