How do i reset the Jeep Liberty check engine light?

The only way to reset the "check engine" light in a Jeep Liberty is to use an OBDII scanner or correct the error that caused it. Check for a loose gas cap. When tightened, the light will go off. Drive the car for at least 15-20 minutes above 25 mph. If You've been starting and stopping excessively, the catalytic converter may be stressed and driving at highway speeds should clear the CEL. Turn the key in the ignition to the "on" and then the "off" position three times in succession and try starting the engine. Disconnect the positive battery cable for 15-20 minutes. Reconnect and repeat the previous "on" and "off" steps outlined above. If these methods fail, keep in mind, the CEL warning is indicating there's an issue with the transmission, O2 sensors or spark plugs and get the vehicle diagnosed immediately.