How do you make the check engine sign go off?

The check engine light is on because the ECU has detected a problem with the emission system. In order to get this light to go off you must repair the problem that caused the light to come on. This will require that you scan the ECU with a scan tool. This will retrieve the code that has been set and lead you in the direction of the problem. Once the problem is repaired you can reset the light and it will not come back on. If you do not repair the problem it will just come back on.