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Diagnosis & Repair

  1. Remove instrument panel fuse cover. Connect scan tester to Data Link Connector (DLC) No. 3. See Figure. Start engine and warm to normal operating temperature. Turn scan tester on. Monitor each oxygen sensor. 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, inspect circuits between ECM and suspect sensor for open or short circuits. Repair as necessary. If circuits are okay, replace oxygen sensor and retest.
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