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Does anyone know if changing the 02 sensor's on the maxima after about 45,000 or 50,000 miles can help performance?
Someone told me I should change them when I did my downpipe and my RT cat. I didn't change them, but just wondered if it would help at all.

Daniel B. Martin

Replacing your Oxygen Sensors will improve performance only if they are defective. Replacing good sensors gains you nothing. There are test instruments made specifically for testing Oxygen Sensors. In addition, any technician with an automotive oscilloscope can test your sensors.

Some Nissan owners report Oxygen Sensor failures as early as 30K miles. In my own experience they last much longer than that.

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Thanks for the info....

pruizgarcia

iTrader: (1)

Mine just failed and had to be replaced. 33K, 99 Maxima SE.

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Martin is really accurate with his info...huh.
Try looking into the Bosch O2 sensors for your car...They may be less expensive than OEM, and may be a better product in regards to performance and longevity.
CYA

bigtexan7

Daniel B. how do you know when the o2 sensor fails? check engine light? 95 auto. thanks

Daniel B. Martin

There are two degrees of failure.

1) The Oxygen Sensor is "dead".
The signal from the Oxygen Sensor is outside the normal range, or completely absent. The Engine Control Module (the computer) turns on the Malfunction Indicator Light and stores one or more Diagnostic Trouble Codes. This failure mode is obvious because of the dashboard warning light.

A dead Oxygen Sensor is a severe failure and should be repaired promptly.

2) The Oxygen Sensor is "lazy".
The Oxygen Sensor still works but it responds slowly to changes in the oxygen concentration in the exhaust stream. There is no MIL or DTC. This failure mode is less obvious. The symptoms are slightly increased fuel consumption, slightly decreased engine power, and a feeling of sluggishness. The throttle response is not crisp, like it was when the car was new. An Oxygen Sensor may become lazy due to high mileage or being "poisoned" by exposure to various substances including leaded fuels, anti-freeze, anti-sieze, and RTV sealants.

Some people refer to a "tired" Oxygen Sensor. This is the same thing as lazy. Both are informal references to a sensor which is still doing its job, but not performing well.

A lazy Oxygen Sensor is not a severe failure and the car may be operated safely.

lucky_777

Daniel,

Is there any way to diagnose "lazy" Oxygen Sensor ??

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All I got to say is....................

Daniel Martin is the man!!!!!!!!!!

Hey Daniel,
Did you write the book on this stuff or what? I don't think anyone is going to stump Mr. Martin....he knows his stuff.

Oh...Daniel, are there just two O2 sensors? On the downpipe, and just behind the cat? (on a 96).

Daniel B. Martin

Yes. There are electronic testers made for this specific purpose. In addition, a technician with an automotive oscilloscope can test Oxygen Sensors. The signal from a healthy sensor varies from a low threshold (around 0.2 volts) to a high threshold (around 0.8 volts), and it sweeps back and forth between those extremes about 10 times per second. If the scope trace shows the Oxygen Sensor signal failing to reach either extreme, or oscillating between them at a frequency slower than 10 cycles per second, that is evidence of a "lazy" sensor.

I've read that a bad Oxygen Sensor can sometimes be rejuvenated by removing it, clamping it in a vise, and heating the sensing tip red hot with a propane torch. This is said to burn off a crust of deposits which interfere with its operation. I've never tried this torch trick myself, so cannot vouch for it's effectiveness. If you have a sensor which is already dead, you have little to lose.

I just did a web search and came across an article about Oxygen Sensors at http://www.volksparts.com/o2sensors.htm
I haven't read the whole thing yet but it looks interesting.

Daniel B. Martin

All '95-up OBD-2 compliant Maxima engines have three Oxygen Sensors. There is one for each bank of cylinders and one just downstream of the catalytic converter.

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Again...Thanks for your help Mr. Martin

An Appreciative Individual...