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Oxygen Sensor (O2)

  1. Start engine and warm to operating temperature. Disconnect oxygen sensor. Connect a DVOM between Purple lead of oxygen sensor and ground. Place meter on the 2-volt scale. Voltmeter reading should increase to greater than .8 volt.
  2. Using another DVOM on the 20-volt scale. Connect voltmeter in series between Purple wire from the ECM and the positive post of battery. Reading on voltmeter connected to oxygen sensor should decrease to a low voltage (less than .3 volt). If reading does not change as specified, replace O2 sensor.
  3. If a second DVOM is not available, install short jumper in Purple wire from the ECM. Hold jumper in one hand and touch positive post of battery with other hand to cause oxygen sensor to produce less than .3 volts. For additional testing procedures, see appropriate TESTS W/CODES article.
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