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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 370 (Engine Control System - Self-Diagnostics - 4.2L) >> Diagnostic Tests >> DTC P0130: Ho2S Circuit (Bank 1; Sensor 1) >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Oldsmobile Bravada, 2003 GMC Envoy XL, 2003 GMC Envoy, and 2003 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Turn ignition on, with engine off. Command the HO2S 1 heater ON with a scan tool. Wait 15 seconds to allow the HO2S 1 heater current to stabilize. Observe the HO2S 1 heater current parameter with a scan tool. Is the HO2S 1 heater current parameter within 0.22-1.56 amps? If yes, go to next step. If no, go to DTC P0135 OR P0141: HO2S HEATER CIRCUIT (BANK 1; SENSOR 1 OR 2) .
  3. Start engine. Allow engine to reach operating temperature. Operate engine at 2000 RPM for 30 seconds. Observe the HO2S 1 voltage parameter with a scan tool. Is the HO2S 1 voltage parameter varying greater than and less than the specified range of 300-600 mV? If yes, go to next step. If no, go to step  5.
  4. Observe the Freeze Frame/Failure Records for this DTC. Turn ignition off for 30 seconds. Start the engine. Operate the vehicle within the Conditions For Running the DTC. See CONDITIONS FOR RUNNING DTC . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to next step. If no, problem is intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 4.2L BRAVADA, ENVOY, ENVOY XL, TRAILBLAZER & TRAILBLAZER EXT article.
  5. Turn ignition off. Disconnect the HO2S 1. Turn ignition on, with engine off. Observe the HO2S 1 voltage parameter with a scan tool. Is the HO2S 1 voltage parameter more than 800 mV? If yes, go to next step. If no, go to step  7.
    6. NOTE: The normal voltage on the high signal circuit is 400-500 mV. The sensor may be damaged if the circuit is shorted to a voltage.
  6. Test the HO2S 1 high signal circuit for a short to voltage. Did you find and correct the condition? If yes, go to step  18. If no, go to step  17.
  7. Connect a 3-amp fused jumper wire between the high signal circuit of the HO2S 1 harness connector on the engine harness side and the low signal circuit of the HO2S 1 harness connector on the engine harness side. Observe the HO2S 1 voltage parameter with a scan tool. Is the HO2S 1 voltage parameter within 400-500 mV? If yes, go to step  9. If no, go to next step.
  8. Remove the jumper wire used in previous step. Test the HO2S 1 heater low control circuit for a short to the HO2S 1 low signal circuit or HO2S 1 high signal circuit. Did you find and correct the condition? If yes, go to step  18. If no, go to step  14.
  9. Remove the jumper wire used in previous step. Connect a 3-amp fused jumper wire from the high signal circuit of the HO2S 1 harness connector on the engine harness side and ground. Observe the HO2S 1 voltage parameter with a scan tool. Is the HO2S 1 voltage parameter within 400-500 mV? If yes, go to step  11. If no, go to next step.
  10. Remove the jumper wire used in previous step. Test the HO2S low signal circuit for an open. Did you find and correct the condition? If yes, go to step  18. If no, go to step  15.
  11. Measure the voltage from the high signal circuit of the HO2S 1 harness connector on the engine harness side to a good ground with a DVOM. Is the voltage more than 1.0 volt? If yes, go to next step. If no, go to step  13.
    12. NOTE: The normal voltage on the low signal circuit is 20-100 mV.
  12. Test the HO2S 1 low signal circuit for a short to voltage. Did you find and correct the condition? If yes, go to step  18. If no, go to step  17.
  13. Test the HO2S 1 high signal circuit for an open. Did you find and correct the condition? If yes, go to step  18. If no, go to step  15.
  14. Test for an intermittent and for a poor connection at the HO2S 1. Did you find and correct the condition? If yes, go to step  18. If no, go to step  16.
  15. Test for an intermittent and for a poor connection at the PCM. Did you find and correct the condition? If yes, go to step  18. If no, go to step  17.
  16. Replace the HO2S 1. After replacing sensor, go to step  18.
  17. Replace PCM. See REMOVAL & INSTALLATION - BRAVADA, ENVOY, ENVOY XL, TRAILBLAZER & TRAILBLAZER EXT article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  18. Clear the DTCs with scan tool. Turn ignition off for 30 seconds. Start engine. Operate vehicle within the Conditions For Running DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  19. Observe the stored information, Capture Info with scan tool. Does scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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