I have a 2001.5 RAM2500 5.9 Magnum Auto

after driving for about an hour my trucks starts to run really rich and the computer puts out this code

P0171 (M) 1/1 Fuel System Lean A lean air/fuel mixture has been indicated by an abnormally rich correction factor.

so I assume the o2 sensor has gone bad because it is tryign to correct for lean mix that does not exist and making my truck run horribly rich, so go to the parts store and they have seperater parts numbers for left and right side before cat, but i only have one o2 sensor before my cat after both sides have joined.

 

anyone have any opinion on this or know thepart number of the o2sensor before the cat?

 

When it gave you the code did it tell you bank 1 sensor 1 if it did it is the O2 sensor before the cat. Most parts stores have two different numbers not because the sensors themseves are different, but because the wiring harness is longer or shorter. You can get a universal sensor and splice into the original harness yourself. You can test them if you have a volt ohm meter. You need to find the sensor wire (it should be the black one) with the truck warm unplug the sensor conect the meter between the two black wires, in Ohms it should be between 0.1 and 1.0 if it is not the sensore is bad. the white wire should be hot and the two gray wires are for the heat circut. I'm shooting from memory but i think that is the right wire combo. Any way you'll be able to tell if you have the meter.