Why does my check engine light stays on? on 1995 Toyota Tercel

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
I could take fuse out and reinstall fuse it will stay off for a couple days then come back on.
It still passes smog test.
(1) Answer
try to disconnect battery connection in a few seconds and then reconnect it,if the light still goes on try to clean or check the following if you don't have diagnostic tool by cleaning the air cleaner ,airflow sensor,throttle valve.If it still goes on start and run the engine and check the ignition coil individually and also the injector by disconnecting the socket connection on it ,if you disconnect the socket individually while the engine is running if you noticed no changing of idle that parts is defective but if you noticed rough idle while disconnecting it means to say that parts is good.