Got a trouble code today while driving my Dakota normally. Did the old Dodge ignition test and Code P0138 came up on my odometer window.

P0138 (M) 1/2 O2 Sensor Shorted To Voltage Oxygen sensor input voltage maintained above normal
operating range.

That is my my service manual says it means. How do I track down what the problem is?

 

O2 might be shot.

 

Does one code cover all of them?

 

no this is bank one, sensor 2. (Drivers rear one) I have the same code.

 

My manunal shows that there are 4 O-2 sensors, one on each manifold and 1 before and one after the converter. How can there be a driver's rear sensor? Maybe I am mis-understanding your Driver's Rear statement.

 

there is 2 mans driver and pas

rear is post cat

do you have a truck with 4 o2 sensors? you may want to check not all of them do...i think just california trucks have four

 

silly me, i assumed all trucks had 4 O2 sensors cause mine does. Heres my setup, let me know if this makes more sense.
First of all you have a Y pipe that comes off of the manifolds right?
In this Y pipe there are 2bulges (Pre-cats)near the top, and a larger one in the rear.
If i remember correctly, there is a sensor before each pre-cat, and one after each pre-cat.
the one that is giving you the trouble is the one on the drivers side closest to the rear of the truck.
Does this help?

 

useally 01+ had the 4 o2 sensor setups, 97-00 didnt, but i think a FEW 2000 did. I know mine only has 2 o2 sensors and 1 cat, while the 01+ R/Ts and daks had 2 pre cats with 2 o2s for each, and one big cat with nothing around it.

 

Just an update. I am replacing the behind the cat oxygen sensor. Found a Denso sensor for $45 with free shipping. Was wondering if my K&N air filter would have caused the trouble code.

 

a k&n air filter wont affect anything.