Oxygen Sensor: Service and Repair

REMOVAL
Note: Never apply any type of grease to the oxygen sensor electrical connector, or attempt any soldering of the sensor wiring harness. For sensor operation, it must have a comparison source of oxygen from outside the exhaust system. This fresh air is supplied to the sensor through its pigtail wiring harness.

The O2S (oxygen sensors) are numbered 1/1, 1/2, 1/3, 2/1 and 2/2.

Fig. 41 Oxygen Sensors - 3.9L (FED/CAL), 5.2/5.9L (FED):

On all 3.9/5.2/5.9L LDC Non-California engines, and certain California 3.9L engines, the upstream and downstream O2S sensors are located at the inlet and outlet ends of the catalytic converter.

Fig. 42 Oxygen Sensors:

On HDC engines, the left and right O2S sensors are located on the left and right exhaust down pipes .

Fig. 43 Pre-Catalyst/Post-Catalyst Oxygen Sensors - 8.0L (CAL):

On HDC engines, the pre-catalyst/post catalyst O2S sensors are located at the inlet and outlet ends of the catalytic converter.

Fig. 44 Oxygen Sensors - 5.2/5.9L (CAL):

On 5.2/5.9L California engines, the 1/1 and 2/1 sensors are located before the mini-cats. The 1/2 and 2/2 sensors are located after the mini-cats.

WARNING: THE EXHAUST MANIFOLD, EXHAUST PIPES AND CATALYTIC CONVERTER BECOME VERY HOT DURING ENGINE OPERATION. ALLOW ENGINE TO COOL BEFORE REMOVING OXYGEN SENSOR.

1. Raise and support the vehicle.
2. Disconnect the wire connector from the 02S sensor.

CAUTION: When disconnecting the sensor electrical connector, do not pull directly on wire going into sensor.

3. Remove the O2S sensor with an oxygen sensor removal and installation tool.

INSTALLATION
Note: Threads of new oxygen sensors are factory coated with anti-seize compound to aid in removal. DO NOT add any additional anti-seize compound to the threads of a new oxygen sensor.

1. Install the O2S sensor. Tighten to 30 Nm (22 ft. lbs.) torque.
2. Connect the O2S sensor wire connector.
3. Lower the vehicle.