code 138 says bank 1 senor 2 o2 high voltage were is it located
on 2003 Dodge Ram 2500

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
would like to know were to find this senor
(2) Answers
Customer Concern:
Diagnostic Trouble Code (DTC) P0138 for the bank 1 downstream sensor is being set.

1. Warm the engine and check the Oxygen Sensor (O2S) operation. On this vehicle the voltage should switch between 2.5 - 3.5 volts.

2. If the voltage is normal, this is an intermittent concern. Carefully inspect the wiring harness.

3. If the voltage is high (above 3.99 volts) unplug the O2S and confirm that the scan tool reads around 5 volts for that sensor. If it does measure the voltage on the return circuit using a Digital Volt Ohm Meter (DVOM), a normal voltage is 2.5 volts. If these voltages check good replace the O2S.
Tech Tips:
Be sure to use an Original Equipment from Manufacturer (OEM) specification oxygen sensor on this vehicle. Most non OEM spec sensors will not work properly with the type of PCM on this vehicle.

Bank one means where the number one cylinder starts and downstream means after the cat.