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 engine
light 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.