Questions and Answers
Maxima O2 Sensors
Q. About one year ago the check engine light came on and my Nissan dealer diagnosed it as a O2 sensor, which I had replaced. Recently the same light reappeared. This time the dealership said BOTH sensors had failed and needed replacement.
Tight on dough, I asked what the consequences were of putting the repairs off. They indicated that there weren't any significant problems that could result but that I really should have the problem fixed.
What do these sensors do and am I hurting the car or its performance by driving with them not operating?
1996 Nissan Maxima SE
77,000 miles
Automatic
Fuel InjectedThanks and great site!
A. The oxygen sensor detects the amount of oxygen in the exhaust gas compared to the outside air. It has a closed-end tube made of ceramic zirconia. The zirconia generates voltage from approximately one volt in richer conditions to zero volts in leaner conditions. The oxygen sensor signal is sent to the ECM. The ECM adjusts the injection pulse duration to achieve the ideal air-fuel ratio. The ideal air-fuel ratio occurs near the radical change from one volt to zero volts.
When they go bad the ECM will substitute a stored value for the missing signal and it will keep you going. You probably won't feel a lot of difference in the way the car performs and you won't really hurt anything, but like the dealer said, you should get it fixed when financial conditions permit.
