gonzo
New member
Does my TJ have a mass air flow sensor? had problems a few months back with recurring 02 sensor code po155, replaced both upstream sensors, now getting po135 and po155 both upstream sensors again. Noticed the tailpipe has a lot of black on the tip recently like it's running rich. 4.0 automatic with 78k miles, could a plugged catalytic convertor cause this. All the fuses are good. Engine seems to be running fine, good power and smooth, starts right up, but have noticed fuel mileage gone down lately. Also changed plugs and coil rack with 02 sensors.
