Oxygen Sensor: Testing and Inspection

To perform a complete test of the O2S sensors and their circuitry, refer to the DRB scan tool and appropriate Powertrain Diagnostics Procedures. To test the O2S sensors only, refer to the following.

A total of 4 oxygen sensors (left, right, pre-catalyst and post catalyst) are used with the 8.0L engine when equipped with the Medium Duty Emission Cycle (MDC) engine package.

Only 2 oxygen sensors (left and right) are used with the 8.0L engine when equipped with the Heavy Duty Emission Cycle (HDC) engine.

Pre-Catalyst/Post Catalyst Oxygen Sensor Locations:

The pre-catalyst O2S sensor is located on the inlet end of the catalytic converter.

The post catalyst O2S sensor is located on the outlet end of the catalytic converter.

Left/Right Oxygen Sensor Locations:

The left and right 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 terminal of the sensor connector. Resistance should be between 4.5 ± 0.5 ohms and 7 ohms. Replace the sensor if the ohmmeter displays an infinity (open) reading.