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Oxygen Sensor

  1. Remove 2-pin oxygen sensor connector from wiring harness socket. Connect ohmeter across White leads of oxygen sensor to check resistance of oxygen sensor heating element. Resistance should be about 4 ohms.
  2. Connect voltmeter (set on 2 volt scale) between Black lead of sensor and ground. Start engine. As engine temperature begins to rise, sensor will generate a low voltage signal.
  3. A lean mixture (caused by a small vacuum leak) will generate a voltage reading close to 0 volts. A rich mixture will generate a voltage reading close to 1 volt. Reconnect sensor leads.
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