I think my O2 sensor is bad

[slickroger]

Hi is there more than one O2 sensor on a 2001 pathfinder?are they cleanable or do they have to be replaced?If Cleanable what do i use?If it needs to be replaced is it easy, im semi-mechanically inclined more Electrical?MAF = O2?

Dumb questions need answers too!

Thanks Guys and Gals

[slickroger]

Im going to try to go by a Mr.Lube or something after work to find out what the code is, which i assume would make answering my questions easier.

do they charge $$$$ to just read a code for you and clear it. someone brought this up recently i believe?

[Transtek]

There are 4 O2 sensors: 2 on the front of the engine and 2 near the cats on the exhaust side.They cannot be cleaned. You need the code to know which one has failed. Not too difficult to replace really, just the right sized spanner and a bit of patience trying to thread the rear ones around the back of the engine.BTW, buy original OEM sensors, so there's no cutting/splicing to do.There was also a thread on here a while ago about after changing a rear O2 sensor, you should get your CPU reprogrammed at the dealers. (I haven't done that but supposedly failing to do so could lead to premature failure of the other sensor)Hope that helps.

[slickroger]

I went to Mr. Lube the code is

P0138Bank1 Sensor2 O2 circuit High Voltage

What does that mean which sensor is it and where can i locate it.

Thanks Nico Clubbers

[Transtek]

This is the rear sensor on bank 1 (passenger side when facing your Pathy from the front of engine). It's a white plug that goes behind the engine to near the cats on the underside. You can see the location in this image



Its the one indicated in the left diagram. Disconnect and carefully pull down from underneath the truck. Carefully unscrew the old one and then thread the new one down behind the engine, install the new sensor, making sure not to cross thread it.

[slickroger]

Thanks for the help