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Diagnosis & Repair

  1. Connect scan tool to Data Link Connector (DLC) No. 3. 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 are okay, replace oxygen sensor and retest.
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