recurring Pathfinder O2 sensor failure or is this something else?

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

Reply to
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EFI temp sensor? Could just be corroded sensor, the plug or both?

Reply to
Steve T

Nissan does many things right. But they suck at making (or buying) O2 sensors. It could be that your O2 sensor is so bad that you're burning way too much fuel, and that would cause black smoke and lower your engine temperature. I'm on my fourth Nissan (currently a QX4), and my girlfriend has an I30t, and they have all been through multiple O2 sensors. Next time, I may try a Bosch sensor just to see if they have better longevity.

Reply to
ppointer

Check your oxygen sensor & see if you see any of the following:

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If your oxygen sensor appears to be okay, then check your Engine Coolant Temperature Sensor:
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It's possible that you are getting a faulty signal from your Engine Coolant Temperature Sensor to your Engine Control/Management Unit, (ECU / ECM). From what I am aware, the Engine Coolant Temperature Sensor is used as part of your emission control system. When the engine is cold, the signal from the ECTS tells the ECU to dump more fuel into the intake manifold so as to warm up the engine faster and get the catalytic converter to filter out the noxious emissions. Once the engine is warmed up the signal from the ECTS changes & tells the ECM to reduce the excess fuel into the intake manifold. However if the ECTS is defective, the ECM won't get that signal. As a result the ECU may be dumping more fuel into your intake manifold burning out both your oxygen sensor AND catalytic converter. Have you noticed reduced gas mileage with your rough idle lately? Check your spark plugs to get a better idea.
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Try checking the above & see what results you get.

Anyhow, hope this helps... ID

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Reply to
Idlafie

Might want to check the cigarette lighter too. I heard if it's bad, the OBD II can give false codes.

Reply to
Meat-->Plow

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