I opened up fuel cap to release pressure in tank to change fuel filter. Forget to put fuel cap back on before starting the car. Now, check engine light is on. Will the light turn off by itself after a few days of cycling the system? or Do I must purchase a code reader to manually reset the light? or Can I un-hook the battery for 1/2 hour as people suggest? (hate to re-sync all those electrical equips). I hate to have to drive it back to the dealer for such a minor thing. Please advise? Thank you!