The engine symbol (not the “Engine Maint. Req.” light, but the actual image-of-an-engine light) has been coming on and going off for the past 3 months. The car has 76,000 miles and is in great condition overall. When the light comes on, there’s no discernible change in the way the car rides or feels. Each time I’ve gotten close to taking it in for service, the light has gone off, so I’ve decided not to spend the money. Is it possible that putting fuel-injector cleaner into the gas tank periodically actually caused the problem? Since the first time it came on back in December, I’ve put a bottle of fuel-injector cleaner in and there seems to be a correlation with the light going off again anywhere from 1 mile to 50 miles later.
No need to spend any $$ for a diagnosis. Take it to an auto parts chain store and have the stored “code” read for free. Write down the code designator letters and digits, post the code back here, and see what people think.
If you notice the light coming on right after you fill the gas tank and goes out a couple days later, then you are overfilling the gas tank and saturating the charcoal canister. Stop on the first click.
The code should be stored for ten drive cycles after the light goes out, but as suggested, most auto parts stores will read the code for free. Write down the code and post it here. Don’t bother with the explanation given you at the parts store, just post the code. It will be a P0 followed by three more numbers like P0446