You start by having it checked for codes. The light comes on because the computer has detected a fault. You need to know the code to know what to repair.
Check your fluid levels.
Fix the problem causing them to be on.
To reset the check engine light unplug the battery for 30 minutes. If the issues still persists the light will still light up when reattached.
There is an engine misfire, probably spark plugs issue.
this is for safety so engine does not get ruined,check oil level!!
Get the computer scanned to see what the problem is.
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.
Disconnect the negative battery terminal for at least 30 seconds.
Any failure that can increase tailpipe emissions.
If the check engine light is illuminated, start with scanning for codes.
The most likely cause o f the check engine light is that the belt was not tightened properly. It may also be that the belt stretched and needs to be retightened.
I am not sure of the other 4 reasons But in my experience the top reason your check engine light comes on is because your gas cap isn't tightened all the way.