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Home >> Pontiac >> 2001 >> Firebird Formula, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 5.7L >> Diagnostic Tests >> DTC P0140: Ho2S Circuit Insufficient Activity - Bank 1, Sensor 2; P0160: Ho2S Circuit Insufficient Activity - Bank 2, Sensor 2 >> Diagnostic Procedures

Diagnostic Procedures

  1. If powertrain diagnostic system check was performed, go to next step. If powertrain diagnostic system check was not performed, go to POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under DIAGNOSTIC SYSTEM TESTS. After performing powertrain diagnostic system check, go to next step.
  2. Start engine and run to normal operating temperature. Increase engine speed to about 1200 RPM for 2 minutes. Using scan tool, select ENGINE 1 DATA LIST and monitor suspect HO2S voltage. If voltage reading is 350-550 mV, go to next step. If voltage reading is 350-550 mV, go to step  4.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for at least 30 seconds. Start engine and operate vehicle within conditions required for diagnostic to run, and as close to conditions recorded in FREEZE FRAME and/or FAILURE RECORDS as possible. Select DTC function, and then enter DTC. If scan tool indicates that test failed this ignition, go to next step. If scan tool does not indicate that test failed this ignition, see DIAGNOSTIC AIDS .
  4. Turn engine off. Turn ignition on. Raise and support vehicle. Locate and disconnect suspect HO2S connector. See Figure. Connect a jumper wire between ground and suspect HO2S connector terminal "A" (Tan/White wire for bank 1, sensor 2; Tan wire for bank 2, sensor 2). Connect a second jumper wire between ground and suspect HO2S connector terminal "B" (Purple/White wire for bank 1, sensor 2; Purple wire for bank 2, sensor 2). Turn ignition on. Monitor HO2S voltage with scan tool. If voltage reading is less than 200 mV, go to step  8. If voltage reading is more than 200 mV, go to next step.
  5. Remove both jumper wires from HO2S connector. Using DVOM, measure voltage between ground and HO2S connector terminal "A". If voltage reading is about 5 volts, go to next step. If voltage reading is not about 5 volts, go to step  7.
  6. Turn ignition off. Locate PCM and disconnect connector C1. See Figure. For bank 1, sensor 2, check for open in Purple/White wire between HO2S connector terminal "B" and PCM connector C1 terminal No. 68. See Figure. For bank 2, sensor 2, check for open in Purple wire between HO2S connector terminal "B" and PCM connector C1 terminal No. 65. Repair as necessary. After repairs, go to step  12. If circuit is okay, go to step  10.
  7. Turn ignition off. Locate PCM and disconnect connector C1. See Figure. For bank 1, sensor 2, check for open in Tan/White wire between HO2S connector terminal "B" and PCM connector C1 terminal No. 28. See Figure. For bank 2, sensor 2, check for open in Tan wire between HO2S connector terminal "B" and PCM connector C1 terminal No. 25. Repair as necessary. After repairs, go to step  12. If circuit is okay, go to step  10.
  8. Check for poor connection at HO2S connector. Repair as necessary. After repairs, go to step  12. If connection is okay, go to next step.
  9. Replace suspect HO2S. See REMOVAL, OVERHAUL & INSTALLATION - CARS article. After replacing sensor, go to step  12.
  10. Check for poor connection at HO2S terminals of PCM connector. Repair as necessary. After repairs, go to step  12. If connection is okay, go to next step.
  11. Replace PCM. See REMOVAL, OVERHAUL & INSTALLATION - CARS article. After replacing PCM, go to next step.
  12. Using scan tool, clear DTCs. Turn ignition off for at least 30 seconds. Start engine and allow it to reach normal operating temperature. Operate vehicle within 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, go to step  2
  13. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no undiagnosed DTCs are displayed, system is okay.
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