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Home >> Oldsmobile >> 1997 >> Bravada >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - 4.3L >> Diagnostic Trouble Codes >> DTC P0140 - Ho2S Insufficient Activity Bank 1, Sensor 2 >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the BASIC TESTING - 4.3L article. Retrieve and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
  2. Start engine and allow it to reach operating temperature. Place gear selector in Park or Neutral, and apply parking brake. Increase engine speed to greater than 1200 RPM for 2 minutes. Using scan tool, read LOOP MODE. If scan tool displays CLOSED LOOP, go to step 5). If scan tool does not display CLOSED LOOP, go to next step.
  3. Turn ignition off. Disconnect HO2S connector. Connect a jumper wire between HO2S harness connector signal and ground circuits, and chassis ground. Turn ignition on, engine off. Read HO2S BANK 1 SENSOR GROUND voltage. If voltage is less than 0.2 volt, go to step 7). If voltage is 0.2 volt or greater, go to next step.
  4. Remove jumper wire. Turn ignition off. Reconnect HO2S connector. Disconnect Blue VCM connector. Connect a test light between Blue VCM harness connector signal circuit and battery voltage. If test light illuminates, go to step 6). If test light does not illuminate, go to step 9).
  5. DTC P0140 is intermittent. If any additional DTCs are set, diagnose affected DTCs. If no additional DTCs are set, see DIAGNOSTIC AIDS.
  6. Check HO2S harness connector signal circuit for open. If open is found, go to step 11). If no open is found, go to step 8).
  7. Check HO2S for faulty connection. If faulty connection is found, go to step 11). If connection is okay, go to step 10).
  8. Check VCM for faulty connection. If faulty connection is found, go to step 11). If faulty connection is not found, go to step 12).
  9. Repair open ground circuit. After repairs, go to step 13).
  10. Replace HO2S. After replacing sensor, go to step 13).
  11. Repair circuit as necessary. After repairs, go to step 13).
  12. Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
  13. Using scan tool, select DTC, CLEAR INFO function. Start engine and allow it to reach operating temperature. Using scan tool, select DTC, SPECIFIC function and enter DTC P0140. Operate vehicle within conditions required to set DTC. If scan tool displays RAN AND PASSED, go to next step. If scan tool does not display RAN AND PASSED, return to step 2).
  14. Using scan tool, select Read and Record INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs. If no DTCs are displayed, system is okay.
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