Oxygen Sensor: Testing and Inspection

To perform a complete test of the O2S sensors and their circuitry, refer to Powertrain Management/Computers and Controls/Testing and Inspection/Procedures/Diagnostic Charts. To test the O2S sensors only, refer to the following:

Fig 33 Upstream Oxygen Sensor:

The upstream O2S sensor is located on the exhaust pipe.

Fig 34 Downstream Oxygen Sensor:

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

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 4.5 ± .5 ohms and 7 ohms. Replace the sensor if the ohmmeter displays an infinity (open) reading.