Two years ago My 93 pathfinder was running in a little rough, and then after about 5 months, it would barely at all run choking out black smoke. About 30 000KM ago, the nissan dealer diagnosed and replaced an O2 sensor and it has run fine since.
It is starting to do this again. I have been told that a faulty catalytic converter would shorten O2 sensor lifespan. I would assume after 140 000 KM the cat converter is probably getting marginal even though the engine burns practically no oil.
I have not seen the service engine light come on through the earlier failure, or the recent problem we are starting to see. I am wondering if the problem might not be the O2 sensor but something else. One thing I have notices is that the temperature guage is reading low. Maybe it needs a new thermostat.
Are there other areas that I can look? I have the factory service manual that outlines how to check just about anything but I am not sure where to look. Being a very intermittant problem makes it worse.
Thanks for any help
Chris To send me e-mail remove the sevens from my address.
Chrisd