o2 sensor
 

Every 4-6 months my air/fuel guage jumps to full rich and stays there at all driving conditions. At Idle or cruse or acceleration it just stays at full rich. After I replace the 02 sensor the guage returns to normal operation. The car itself never acts up, only the air/fuel guage. Because I replace them often I am using the Bosch universal non-heated o2 sensor. My mods include intake, downpipe, catback, pullies, and pettit computer. About a year ago my air pump quit so I now bi-pass it. Could the combination of my pettit computer and no air pump be creating an overly rich fuel mixture which is "fouling out" my o2 sensor? Does this make sense? Does anyone without an air pump have this problem?
Mike