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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 P0141 - Ho2S Heater Circuit Bank 1, Sensor 2 >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. If engine has been operating, allow engine to cool down for at least one hour before proceeding with test. Turn engine off. Turn ignition on, with engine off. Using scan tool, select ENGINE 1 DATA LIST and monitor HO2S voltage. If HO2S goes from bias voltage to less than 300 mV or greater than 700 mV, see DIAGNOSTIC AIDS. If HO2S does not go to bias voltage or 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 a test light to chassis ground. Probe ignition feed circuit at HO2S harness connector at PCM side. If test light illuminates, go to next step. If test light does not illuminate, go to step 7).
  5. Connect test light to HO2S ignition feed and HO2S heater ground circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 8).
  6. Using DVOM, check resistance between HO2S 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 to HO2S. After repairs, go to step 12).
  8. Repair open in HO2S heater ground circuit. After repairs, go to step 12).
  9. Check for poor HO2S harness terminals and replace as necessary. After replacing terminals, go to step 12). If HO2S harness terminals are okay, go to next step.
  10. Replace HO2S. After replacing sensor, go to step 12).
  11. Locate and repair short to ground in HO2S feed circuit and replace fuse. After repairs, go to next step.
  12. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter the DTC P0141. Operate vehicle within the conditions that set the 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, diagnose affected DTC(s).
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