I didn't get a CEL with my 96 Mazda 3.0 litre RWD truck. When I bought my used truck in 2000 (just over 60,000 km), I was getting lousy gas mileage in the city and on the hwy (around 12 or so mpg). After going thru a number of mechanics, the poor gas mileage was attributed to two O2 sensors. Never ever got a CEL that was related to the O2 sensors.
2010 Ford Ranger FX4
Armaguard sprayed on bed liner
Truxedo Low Pro QT tonneau cover
Studded General Altimax Arctic P245/75-16 winter tires on black steelies