Any car sold in the US after 1996 is required by law to comply with the OBD-II standard, meaning any OBD-II code-reading device can communicate with the ECU on any post-1996 car. Occasionally the readout you get back will be a proprietary code that the reader doesn’t translate into plain english, but a quick web search of the code will show that, for example, error code “P1506” relates to an air sensor problem on Ford vehicles.
As has been noted, if the “check engine” light is on, your car may be putting out more emissions than allowed. Whereas some of these fault conditions are harmless to the vehicle itself (e.g. a cracked charcoal evap cannister or loose fuel tank cap), other conditions (e.g. a lean operating condition on one or more cylinders, or consistent misfire) can cause expensive damage if left untreated for a long time. Best advice is to diagnose the problem at your earliest convenience; then you can decide whether it needs fixing promptly or it can wait.
You can buy your own scan tool for as little as $25. If you’re strapped for cash, many auto parts stores - if you can get your car to one - will come out to the parking lot and scan your ECU free of charge; they’re willing to do this for you because usually you’ll step inside and buy the needed replacement part from them, a win for everybody involved.
Some fault codes are “latching,” which means they won’t reset themselves even after the problem has been fixed (or has spontaneously cured itself); you will need the scan tool to reset the fault after the repair work is done. Other fault codes will clear themselves when the problem goes away - either immediately, or after the problem has been absent for some set period of time, like X number of miles or X engine starts. In the past I’ve reset the error code just to see if it comes back right away; if it does, I know I’ve got an actual persistent problem that needs to be addressed; if it goes away and stays gone, then all’s well.
This has been our experience as well, and one caveat to the above – simply checking and if needed tightening the gas cap will generally not cause the “Check Engine” light to stop, even if that is the reason why it came on. Turning the car off and restarting it after getting the warning light, checking for and tightening the gas cap, will generally result in it staying off if the loose gas cap was in fact the cause.
Before we sold our Kia Sedona, it would do this quite a bit. We took it in the first few times, then realized that it was always the gas cap. We also eventually realized that the light would turn itself off after the second gas refill following the light coming on.
Thanks for the input - turns out it was P1300 - Random Misfire. Not too unexpected, since it was engine was missing and fuel injector cleaner made the engine stop missing.
Seems unlikely. The car is now in the just give me a reason to replace you phase. I buy a car new and keep it until it dies, but I don’t *need *to stretch its life at this point. It is more like inertia that keeps me from going and getting a new one. If it lasts until inspection, I may have them replace the spark plugs and wiring harness, but we’ll see. The last estimate I got was 400+ for the work, which is way cheaper than a new car, but the danger is, how many other things will need replacing? As a single man, I am also not tolerant of a car that may leave me stranded - I have no one to call. Also, last summer it was clearly struggling to keep the car cool, and I absolutely will not drive a car without AC.
Wow, is this backwards. Continuing to run it with worn spark plugs and spark plug wires (not wiring harness, that’s something different) tends to overstress the ignition module and coil(s) and greatly increases the chance of getting stranded.