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Oxygen (O2) Sensor Current Feed & Heater Resistance

  1. Connect voltmeter between ground and terminal No. 1 of 2-wire connector located next to firewall. Voltage reading should be battery voltage. Remove ground wire from fuel injection ECU terminal No. 20.
  2. Connect ohmmeter between oxygen sensor harness terminal No. 2 (Black wire) and ground. Connector is located next to firewall. With a cold oxygen sensor, resistance should be 2-3 ohms. With a oxygen sensor warmer than 660°F (350°C), resistance should be 7-14 ohms. Replace oxygen sensor as necessary.
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