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Diagnosis & Repair

  1. Connect scan tool to Data Link Connector (DLC) No. 3 connector. See Figure. Start engine and warm to normal operating temperature. Using scan tool, monitor bank No. 1, sensor No. 1 and bank No. 2, sensor No. 1. Snap accelerate engine 3 times. Sensors should indicate a rich signal (.45 volt or more) at least once.
  2. If a rich signal is indicated for both sensors, replace ECM and retest. If either sensor does not display a rich signal, check for open or short circuit in wiring harness between ECM and suspect sensor. Repair as necessary. If wiring harness is okay, replace oxygen sensor and retest.
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