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Home >> Buick >> 1996 >> Roadmaster Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control Systems - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P0161 - Ho2S Heater Circuit Bank 2, Sensor 2 >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
    NOTE: If engine has been operating, allow engine to cool for about 1 hour before proceeding with tests.
  2. Turn ignition off. Turn ignition on, with engine off. Using scan tool, select ENGINE 1 DATA LIST and monitor HO2S voltage. If HO2S voltage goes from bias voltage to greater than 700 mV or less than 300 mV, see DIAGNOSTIC AIDS. If HO2S voltage does not go from bias voltage to less than 300 mV or greater than 700 mV, go to next step.
  3. Check HO2S ignition feed fuse. If fuse is faulty, go to step 11). If fuse is okay, go to next step.
  4. Raise and support vehicle. Disconnect HO2S harness connector. Connect test light to chassis ground and probe ignition feed circuit at HO2S harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 7).
  5. Connect test light between ignition feed circuit and heater ground at HO2S harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 8).
  6. Using DVOM, check resistance between ignition feed and heater ground at HO2S harness connector. Resistance should be 3.5-14.0 ohms. If resistance is as specified, go to step 9). If resistance is not as specified, go to step 10).
  7. Repair open in HO2S ignition feed circuit. After repairs, go to step 12).
  8. Repair open in HO2S heater ground circuit. After repairs, go to step 12).
  9. Check for poor terminal connection at HO2S connector. Repair or replace terminals. After repairs, go to step 12).
  10. Replace HO2S. After replacing HO2S, go to step 12).
  11. Locate and repair short to ground in HO2S ignition feed circuit and replace fuse. After repairs, go to next step.
  12. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0161. Operate vehicle within the conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2).
  13. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.
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