Many GM vehicles have a box near the battery with a bunch of fuses. Pull the cover so that you can see the fuses, look for a button that says "oil" or something similar. With the key on and the engine NOT running, push and hold the button for about 10 seconds. If yours is different, look in the operators manual for instructions.
picture of engine
yes, and also, using the wrong gas cap could also cause the light to come on. It may even cause your engine to stall
Why? Just reset it.
The light is on to tell you to go get to codes scanned. (A more detailed description is available in your Owners Manual.) Many auto parts stores will scan codes for free.
That requires an OBDII engine scanner.
The service engine soon light means there is regular scheduled maintenance due on the vehicle. Oil change, tire rotation, transmission service, etc. All this is spelled out in your owners manual. This is different than the Check Engine light which means the ECU has detected a problem with the emissions system. You have to manually reset the light according to the instructions in you owners manual. Disconnecting the battery will not reset the light.
disconnect the battery for 30 seconds
You need to hook the computer up to a scan tool to read the codes. That will tell you why the light is on.
unhook the positive on the battery for 5 min. This should reset your check engine light if it doesnt then you still have issues.
Have vehicle scanned to determine the problem and have codes cleared
The service engine light is the same thing as a check engine light.
There are pages of things that can turn the light on. You need to have it checked for codes. See related questions below.