How do you reset engine light after gas cap was left off?

To reset the engine light after leaving the gas cap off, first, ensure the gas cap is securely tightened. Then, you can either disconnect the car battery for about 15 minutes or use an OBD-II scanner to clear the trouble codes. Alternatively, simply driving the vehicle for a few cycles may cause the light to reset automatically if the issue is resolved. Always check for any additional issues if the light remains on.