Heavy Duty Engines

Fig. 63 Left/Right Oxygen Sensor Location:

The left and right 025 sensors are located on the left and right exhaust downpipes.

Each O2S heating element can be tested with an ohmmeter as follows:
Disconnect the O2S sensor connector. Connect the ohmmeter test leads across the white wire terminals of the sensor connector. Resistance should be between 5 and 7 ohms. Replace the sensor if the ohmmeter displays an infinity (open) reading.