Oxygen Sensor: Service and Repair

REMOVAL
Never apply any type of grease to the oxygen sensor electrical connector, or attempt any soldering of the sensor wiring harness.

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

Fig.38 Pre-catalyst/Post Catalyst Oxygen Sensors - HDC Engines:

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

Fig.39 Oxygen Sensors - 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 O2S 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
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.