Postby smj999smj » Sat Jul 28, 2012 10:31 pm
O2 sensors can fail in a number of ways so symptoms can vary. It can cause an engine to run too lean or can cause it to run too rich. Sputtering, excessive gas consumption, fouling spark plugs are all signs of an engine running too rich. Surging, pinging under load, blistered spark plugs, misfiring are all signs of an engine running too lean. The O2 sensor is the ECM's main input for determining how much fuel to inject into the engine. They do tend to lose efficiency over time; if you have a WD21 Pathy with its original O2 sensor, you've certainly gotten your money's worth out of it and should replace it just for sake of routine maintenance. There is a procedure to test the sensor using an ohmmeter in the FSM.
As far as replacement sensors, yes, there is a wide range of choices. As far as the sensor, itself, most of them are pretty similar. The biggest differance is in fitment and their choice of element in the sensor. There are two main types of sensors: universal fit and direct fit. Universal fit sensors use the harness and connector of your old sensor while direct fits are made to plug and play, so to speak. Thus, universal fit sensors are a lot cheaper, but can be prone to problems if the terminals in the original connectors are weak or worn or the splice connections fail. For those reasons, I recommend spending a little more and getting a direct fit sensor. As far as brands, NTK (a division of NGK) and Bosch are both OEM suppliers of O2 sensors to Nissan. Denso is an OEM supplier to Toyota. I have no problem with any of those brands. You can usually get O2 sensors at a good price at Rockauto.com. Now, whether replacing the O2 sensor will fix your problem, I cannot say. I would recommend checking the fuel pressure with a gauge and seeing if it's within spec (you may have a bad regulator causing high fuel pressure). Also, make sure it's not due for a tune-up; if you repace any ignition componants, stick with genuine Nissan or NGK brand parts.