All Maximas are 6 cyl. Most have one O2 sensor for each bank located on the exhaust manifold. Many have a 3rd sensor after the Catalytic convertor. This one often goes first. 89-94 Maximas have one. 95-98 have three, two fronts B1 and B2 and one rear. 99 and 00-03 have four, B1 and B2 front and rear. 04 and up have 2 air fuel ratio sensors and 2 rear 02 sensors.
Click here (the TSB's on O2-sensors have diagrams for the locations and descripions of the individual sensors).
with your hands and some tools
If bank 1 and bank 2 sensor bad car won't start
On a 2005 Nissan Maxima, the Bank 1 Sensor 1 O2 sensor is located on the exhaust manifold, upstream of the catalytic converter. It is positioned on the driver's side of the engine, near the front. You may need to access it from underneath the vehicle or from the engine bay for replacement or inspection.
I found this great site about Nissan O2 and its location to fix.. http://maxima.theowensfamily.com/tsb/index.asp?year=2000&tsb=none Search for NTB02-051a All O2 Sensor Replacements Thanks... Jim
bank one is drivers side, sensor 2 is rear O2 sensor(oxygen sensors are screwed into exhaust pipes)
Answer I found this great site about Nissan O2 and its location to fix with diagrams!
What problems will a bad speed sensor cause on a 1999 Nissan Maxima
one
Trouble code P0139 means: O2 Circuit Slow Response (Bank 1, Sensor 2) Replace the downstream O2 sensor
where is the camshaft sensor in a 96 nissan maxima 3.0
Did you figure out where this sensor is located
Have you replaced the distributor cap? I have a 94 Maxima that would not start due to a cracked distributor cap. (Check for sparks under the hood when it's dark.)