This pertains to my 01 Ram 1500 5.9L Regular Cab Short Box. A couple months ago after changing out the water pump I had my check enginelight come on. I brought up the code P0138 on the odometer. Truck ran fine, took it to Auto Zone and they cleared out the light. Just last week the truck is still perfect and the day of my inspection, the light comes on again. Truck runs fine. Due to the NYS emissions I had to wait another day to bring it back. One of my buddies reset the light at dealership. I ran it through a drive cycle and the next day it passed fine. Exactly a week later today it came on again. I took it to Auto Zone and asked them about my problem. I don't know about their computer, but it said I have 3 o2 sensors. I told the guy I have 2. One on both sides of the cat. The way the code reads is HO2S Circuit High Voltage Bank 1 Sensor 2. We come to the conclusion it's the sensor after the cat? I told him fine because I have never replaced a sensor on this truck. He sold me a Bosch that is OEM. I could have bought one that you splice the wires...I said no way. Now what my question is that by replacing the sensor, does this solve my problem? The truck never misses a beat. Replaced plugs at 30,000 miles. Everything is stock. The guy at Auto Zone tells me that o2 sensors should last 70,000 miles, not the 50,000 I have. I would appreciate the help. Thanks.