Re: Check engine light
 

on my 1989 YJ, I had to disconnect the wires that run from the light on the
dash to the counter mounted under the dash. On my YJ the only thing the
counter does is count the number of miles your Jeep goes. After about 72,000
miles the light comes on and stays on. You can't turn it off. It signals that
it is time to change the O2 sensor. The only way to get the light to go off is
to unplug the counter, or to replace the counter for $45. The new counter will
set the light off at around 144,000 miles letting you know it's time to change
the O2 sensor again. Or you can save the $45 and just remember when to change
the O2 sensor.

It explained in detail in a Hayne's manual.