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Home >> Pontiac >> 2001 >> Firebird Base, 2D Convertible, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 3.8L >> Diagnostic Tests >> DTC P0134: Ho2S Circuit Insufficient Activity - Bank 1, Sensor 1 >> 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 CHECKS. After performing powertrain diagnostic system check, go to next step.
    NOTE: Before performing next test step, ensure all HO2S are secure in exhaust pipe. A loose sensor can cause DTC to set.
    2. NOTE: If any DTCs except HO2S DTCs are present, diagnose affected DTCs first. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
  2. Start engine and run to normal operating temperature. Increase engine speed to 1200 RPM for 2 minutes. Using scan tool, select ENGINE 1 and note suspect HO2S voltage. If voltage varies from less than 400 mV to more than 500 mV, go to next step. If voltage does not vary from less than 400 mV to more than 500 mV, go to step  4.
  3. Turn engine off if necessary. Turn ignition on. Using scan tool, read and record FAILURE RECORDS data. Turn ignition off for 30 seconds. Start engine and operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool indicates DTC failed this ignition, go to next step. If scan tool does not indicate DTC failed this ignition, see INTERMITTENT TROUBLE CODE DETERMINATION  under SELF-DIAGNOSTIC SYSTEM.
  4. Check for an exhaust leak, an incorrectly installed HO2S or damaged wiring. After repairs, go to step  15. If no problems were found, go to next step.
  5. Disconnect suspect HO2S. Turn ignition on. Connect jumper wire between HO2S connector terminal "A" (Tan/White wire on Bank 1, Sensor 1; Tan wire on Bank 2, Sensor 1; Gray wire on Bank 1, Sensor 2) and ground. Using scan tool, observe HO2S voltage parameter. If scan tool indicates HO2S voltage is more than 400 mV, go to next step. If voltage is 400 mV or less, go to step  10.
  6. Remove jumper wire. Using DVOM connected to ground, measure voltage to HO2S connector terminal "B" (Purple/White wire on Bank 1, Sensor 1; Purple wire on Bank 2, Sensor 1; Dark Blue wire on Bank 1, Sensor 2). If voltage is about 4.5 volts, go to next step. If voltage is not about 4.5 volts, go to step  9.
  7. Using a DVOM, measure voltage between ground and terminal "A" of HO2S (Tan/White wire on Bank 1, Sensor 1; Tan wire on Bank 2, Sensor 1; Gray wire on Bank 1, Sensor 2). If voltage reading is about 5 volts, go to step  11. If voltage reading is not about 5 volts, go to next step.
  8. Check wiring to HO2S terminal "A" (Tan/White wire on Bank 1, Sensor 1; Tan wire on Bank 2, Sensor 1; Gray wire on Bank 1, Sensor 2) for an open or high resistance. Repair as necessary. After repairs, go to step  15. If connections are okay, go to step  13.
  9. Check wiring to HO2S terminal "B" (Purple/White wire on Bank 1, Sensor 1; Purple wire on Bank 2, Sensor 1; Dark Blue wire on Bank 1, Sensor 2) for an open or high resistance. Repair as necessary. After repairs, go to step  15. If connections are okay, go to step  13.
  10. Check wiring to HO2S terminal "A" (Tan/White wire on Bank 1, Sensor 1; Tan wire on Bank 2, Sensor 1; Gray wire on Bank 1, Sensor 2) for a short to ground. Repair as necessary. After repairs, go to step  15. If connections are okay, go to step  14.
  11. Check HO2S sensor for poor connections. Repair as necessary. After repairs, go to step  15. If connections are okay, go to next step.
  12. Determine cause of HO2S sensor contamination. Check for oil or coolant consumption, use of improper RTV sealant, or alcohol/contaminated fuel. Replace suspect HO2S. See REMOVAL, OVERHAUL & INSTALLATION - CARS article. After repairs, go to step  15.
  13. Check PCM connectors for poor connections. Repair as necessary. After repairs, go to step  15. If connections are okay, go to next step.
  14. Replace PCM. See REMOVAL, OVERHAUL & INSTALLATION - CARS article. After replacing PCM, go to next step.
  15. Using scan tool, clear DTCs. Turn ignition off for 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.
  16. 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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