For what it's worth, my light started coming on intermittently last month in my '97 6 cyl. I checked to be sure the header bolts were tight, gas cap, etc. Started buying a different brand of gas. Still the light came on intermittently. I cleaned and oiled the K&N air filter, put in a new cap and rotor, and installed Bosch plat plugs, wires and oxygen sensor. My local Jeep dealer is useless, so I didn't go have the system reset for the new oxygen sensor as recommended. The engine light has not come on since I did the "tune-up" and I have been getting 19+ (peak 19.9) mpg on the highway or fast 2 lane roads, and my worst has been a flat 14 mpg in just over 200 miles with a split of town, 2 lane highway and over 60 miles of low range crawling on 4 wheeler and skidder trails (looking for partridge, not heavy off-roading).