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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 274 (Engine Controls - Self-Diagnostics - 2.2L) >> Diagnostic Tests >> DTC P0140: Ho2S Circuit - Insufficient Activity (Bank 1; Sensor 2) >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
  2. Turn ignition on, with engine off. Command the HO2S 2 heater ON with a scan tool. Wait 15 seconds to allow the HO2S 2 heater current to stabilize. Observe the HO2S 2 heater current parameter with a scan tool. Is the HO2S 2 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) .
  3. Start engine. Allow the engine to reach operating temperature. Operate the engine at 2000 RPM for 30 seconds. Quickly cycle the throttle from closed throttle to wide open throttle 3 times while observing the HO2S 2 voltage parameter with a scan tool. Did the HO2S 2 voltage parameter change greater than 200 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 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 - 2.2L & 3.0L VUE article.
  5. Turn ignition off. Disconnect the HO2S 2. Turn ignition on, with engine off. Observe the HO2S 2 voltage parameter with a scan tool. Is the HO2S 2 voltage parameter greater than 800 mV? If yes, go to next step. If no, go to step  7.
    6. NOTE: Normal voltage on the high signal circuit is 400-500 mV. Sensor may be damaged if circuit is shorted to a voltage source.
  6. Test HO2S 2 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 2 harness connector on the engine harness side and the low signal circuit of the HO2S 2 harness connector on the engine harness side. Observe the HO2S 2 voltage parameter with a scan tool. Is the HO2S 2 voltage parameter within 400-500 mV? If yes, go to step  9. If no, go to next step.
  8. Remove jumper wire. Test HO2S 2 heater low control circuit for a short to the HO2S 2 low signal circuit and HO2S 2 high signal circuit. Did you find and correct the condition? If yes, go to step  18. If no, go to step  14.
  9. Remove jumper wire. Connect a 3-amp fused jumper wire from the high signal circuit of the HO2S 2 harness connector on the engine harness side and ground. Observe the HO2S 2 voltage parameter with a scan tool. Is the HO2S 2 voltage parameter within 400-500 mV? If yes, go to step  11. If no, go to next step.
  10. Remove jumper wire. Test HO2S 2 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 2 harness connector on the engine harness side to a good ground with a DVOM. Is the voltage greater than 1.0 volt? If yes, go to next step. If no, go to step  13.
    12. NOTE: Normal voltage on the low signal circuit is 20-100 mV.
  12. Test HO2S 2 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 HO2S 2 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 2. 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 ECM. Did you find and correct the condition? If yes, go to step  18. If no, go to step  17.
  16. Replace HO2S 2. After replacing sensor, go to step  18.
  17. Turn ignition off. Replace ECM. Perform ECM relearn procedure. See ELECTRONIC CONTROL MODULE REPROGRAMMING  under PROGRAMMING. After replacing ECM, go to next step.
  18. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Operate vehicle within the conditions for running the DTC. See CONDITIONS FOR RUNNING DTC . You may also operate vehicle within the conditions observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to step  2. If no, go to next step.
  19. With a scan tool, observe the stored information, Capture Info. Does the 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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