Drove the car to a local auto parts store. The nice man plugged a code reader into the socket near the driver side door:
The code is P0456, meaning slow leak of gas evaporation and 85% the cause is just an old gas cap that can no longer make a perfect seal:
I was going to order a new one from Amazon, but it cost even more than the local store. Drove to the store again the next day and got one for $4.99:
However, the light(s) were back again after 2 or 3 days. I screwed off the negative terminal from the battery for few minutes to reset the lights. Now it's been two weeks and the lights have not come back.
- Check engine light(s) do not necessarily mean an engine problem. They could mean anything, such as just an old gas cap in this case.
- Before going to a dealer, get the code from a local store for free. It is a very simple process.
- If it is a slow leak, try a $5 new cap first, or you might end up paying hundreds of dollars to a dealer.
- The system does evaporation pressure test every two days or so. Therefore the light(s) may still come back 2 to 3 days after a new cap. Just reset the lights again and if they do not come back after 2 or 3 days, then that's it.
- Amazon is no longer so cheap, because its CEO is now more interested in burning the last penny on the Blue Origin rocket than rewarding its shoppers.