Oxygen Sensor: Service and Repair

With Four Wheel Drive (4WD).

Upstream Oxygen Sensor Locations (With 4WD):

Downstream Oxygen Sensor Location (With 2WD):

The upstream O2S sensor is located on exhaust downpipe. The downstream sensor is located near outlet end of catalytic converter.

Pre-Catalyst/Post-Catalyst Oxygen Sensors (With 2WD):

With Two Wheel Drive (2WD): This engine/transmission is equipped with 4 oxygen sensors (pre-catalyst, post-catalyst, left and right). The pre-catalyst sensor is located just before the catalytic convertor. The post-catalyst sensor is located just after the catalytic convertor.

Left/Right Oxygen Sensors (With 2WD):

The left and right oxygen sensors are located on left and right exhaust downpipes.

REMOVAL

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. Snap-On oxygen sensor wrench (number YA 8875) may be used for removal and installation.

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 N-m (22 ft. lbs.) torque.
2. Connect the 025 sensor wire connector.
3. Lower the vehicle.