O2 sensors 2002 qx4

[osageorange4]

What is the function of the O2 sensors on a 2002 QX4 and what will the symptoms be if they fail?

[rgk]

To monitor the amount of oxygen in the exhaust. Simply put, they tell the computer whether the car is running rich or lean. The computer then adjusts parameters accordingly, in order to run properly and comply with emissions standards.

The front O2 sensor (pre-catalytic converter) helps the computer adjust parameters. The rear sensor (post-cat) tells the ecu whether the car is complying with emissions standards.

Generally, when they fail the car runs rich. If they are failing, but not completely failed, they will cause the car to behave strangely.

[asnorton44]

My post-cat 02 sensor has been out for some time and havent noticed a difference.

[osageorange4]

I have the passenger side cylinders all running rich. Keeps fouling out the plugs.

[rgk]

Any engine trouble codes?

[osageorange4]

P0300

[rgk]

Per your other Coil Packs thread, you replaced this sensor, correct?

[osageorange4]

Yes I did. Still get the darn P0300 code. Driving me nuts tracking this issue down

[osageorange4]

None of the plugs are fouling out now though.