The Heated Oxygen Sensor (HO2S) monitors the oxygen content in the three-way catalytic converter and then transmits this information to the Powertrain Control Module (PCM). The PCM then adjusts the air/fuel ratio to provide a rich (more fuel) or lean (less fuel) condition.
See Figures 1 and 2
Perform a visual inspection on the sensor as follows:
- Remove the sensor from the exhaust.
- If the sensor tip has a black/sooty deposit, this may indicate a rich fuel mixture.
- If the sensor tip has a white gritty deposit, this may indicate an internal anti-freeze leak.
- If the sensor tip has a brown deposit, this could indicate oil consumption.All these contaminants can destroy the sensor; if the problem is not repaired, the new sensor will also be damaged.
- Reinstall the sensor.
- Disconnect the Heated Oxygen Sensor (HO2S). Measure the resistance between PWR and GND (heater) terminals of the sensor.
- With the engine hot to warm, the resistance should be between 5.0-30.0 ohms.
- At room temperature, the resistance should be between 2.0-5.0 ohms. The readings are within specification the sensor's heater element is okay.
- With the O 2 S connected and engine running, measure voltage with a DVOM by backprobing the SIG RTN wire of the oxygen sensor connector. The voltage readings at idle should stay below 1.0 volts. When the speed is increased or decreased the voltage should fluctuate between 0-1.0 volts, if so the sensor is okay.
REMOVAL & INSTALLATION
- Open and support the hood with the prop rod.
- Disconnect the negative battery cable.
- If equipped, remove the exhaust manifold heat shield.
- Unplug the Heated Oxygen Sensor (HO2S) electrical connection.
- Using the appropriate size wrench or socket, remove the oxygen sensor.
- Install and tighten the new sensor.
- If removed, install the heat shield.
- Attach the oxygen sensor electrical connection.
- Connect the negative battery cable.