2007 Toyota Corolla check engine light

I don't have enough time left in my life to type the list of possibilities. Here's a link to the first page of fault codes:

https://www.2carpros.com/trouble_codes/obd2/P0100

Your Engine Computer detected a problem, set a diagnostic fault code, and since that problem could adversely affect emissions, it turned the light on to tell you. The first step is to have that code read. Many auto parts stores will do that for you for free. It's important to understand that fault codes never say to replace parts or that they're defective. They only indicate the circuit or system that has a problem, or they describe the unacceptable operating condition. Reading the code is just the first of a long list of steps in troubleshooting the cause of the problem.