- 1). Locate the oxygen sensor connector and insert a long pin into the connector, which contains the white or white/red signal voltage wire. Using a voltmeter, connect the positive probe to the pin and the negative probe to a ground.
- 2). As the engine warms up, monitor the voltage signal. Initially, the voltage signal will be steady at approximately 0.1 volts. After approximately 2 minutes, the voltage from the oxygen sensor will begin to fluctuate between 0.1 and 0.9 volts, which is known as "closed mold."
- 3). Inspect the heater for the oxygen sensor by disconnecting the sensor's electrical connector and attaching to the ohmmeter between the heater terminals. The ohmmeter should display a value between 10 and 40 ohms.
- 4). The supply voltage to the heater should be measured on the harness side of the sensor's electrical connector while unplugged. With the ignition on, there should be voltage. If the meter does not read that any voltage exists, check the circuit between the main relay, the PCM and the sensor.
- 5). If the parameters listed in Step 2, Step 3 or Step 4 are not met, then there is a failed or malfunctioning oxygen sensor that requires replacement.
- 1). Disconnect the negative terminal cable of the battery. Then, disconnect the electrical connector of the oxygen sensor and carefully unscrew the sensor from the exhaust manifold.
- 2). Install the new sensor in place of the old one and tighten securely. Reconnect the electrical connector of the pigtail lead on the wiring harness of the engine.
- 3). If necessary, reset the error codes on the vehicle. Take the car for a test drive to verify that the error codes do not reappear as an indicator light.
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