Check engine light comes on

@jeanie72142 the only real way is by scanning your Buick's OBDII to determine the error code that tripped the sensor which turned the Check Engine Light on. Not sure where you are located, but in the USA places like Autozone and other parts stores offer a free scanning.

There really isn't much else you can do.

Of course, you can try and see if a reset will work. For that you will have to disconnect the battery for about an hour. Then reconnect it and drive your car for about 10 -15 miles or so. See if the light stays off or if it turns back on. This will erase radio presets, clock settings, and even the seat memory. Also, some factory alarms do not like this type of reset.