There are pages and pages of things that can cause a check engine light. You need to have it checked with a scantool. Then the code can be diagnosed and repaired.
How do you reset check engine light for the 2009 Chevy trail blazer?
Random cylinder misfire
Bulb may be blown or has been removed.
The check engine light is triggered by the Engine Control Module (ECM). The ECM receives information from many sensors and determines when to illuminate the check engine light.
It is important to know what the lights on the dashboard mean. To turn off the check engine light a person needs to repair the issues in the engine.
At key on it should come on for a couple second "bulb check".
You have a severe misfire. See related questions below.
The engine will develop a skip and the check engine light will illuminate. The code set in the ecm will direct you to which injector is bad.
To tell you to read the diagnostic codes.
Try disconnecting the battery for 10 minutes. May reset the light--if problem persists light will come back on
The idle speed is NOT adjustable it is computer controled. Is the check engine light on ? if so then you MUST have the engine scanned with an engine scanner to see what is wrong.
You can if you want to but the vehicle won't pass emissions and the check engine light will remain on.