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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 108 (Engine Controls Self-Diagnostics - 2.2L) >> Diagnostic Tests >> DTC P0134: Ho2S Circuit - Insufficient Activity (Bank 1; Sensor 1 - SOHC) >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Pontiac Sunfire, 2002 Pontiac Grand Am, 2002 Oldsmobile Alero, and 2002 Chevrolet Cavalier. 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. NOTE: If any other DTCs are set, except HO2S DTCs, refer to other DTCs first before proceeding with this test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
  2. Engine is at operating temperature. Operate engine at greater than 1200 RPM for 2 minutes. With a scan tool, observe the HO2S 1 voltage parameter. Does scan tool indicate HO2S voltage varying outside the specified value of 400-500 millivolts? If yes, go to next step. If no, go to step  4.
  3. Operate vehicle within Failure Records conditions. Does the scan tool indicate this DTC failed this ignition? If yes, go to next step. If no, go to DIAGNOSTIC AIDS .
  4. Inspect and test for exhaust leak, or improperly installed HO2S 1. Did you find and correct the condition? If yes, go to step  13. If no, go to next step.
  5. Turn ignition off. Disconnect HO2S 1. Jumper the HO2S 1 low signal circuit to a good ground. Turn ignition on, with engine off. Measure the voltage on the HO2S 1 high signal circuit on the PCM side using a Digital Multimeter (DMM) that is connected to a good ground. Does the voltage measure within 351-551 millivolts? If yes, go to next step. If no, go to step  8.
  6. Jumper the high signal circuit to the low signal circuit, PCM side. With a scan tool, observe HO2S 1 voltage parameter. Does the scan tool indicate HO2S 1 voltage at or about 0 millivolts? If yes, go to step  9. If no, go to next step.
  7. Test the low signal circuit for an open or high resistance or short to voltage. Did you find and correct the condition? If yes, go to step  13. If no, go to step  11.
  8. Test the high signal circuit for an open or high resistance or short to voltage. Did you find and correct the condition? If yes, go to step  13. If no, go to step  11.
  9. Inspect for poor connections at the harness connector of the HO2S 1. Did you find and correct the condition? If yes, go to step  13. If no, go to next step.
    10. NOTE: Determine the cause of contamination before replacing the sensor.
  10. Inspect and test for fuel contamination, engine oil or coolant consumption, or improper use of RTV sealant. Remove the HO2S and visually inspect the portion of the sensor exposed to the exhaust stream in order to check for contamination. If contaminated, the portion of the sensor exposed to the exhaust stream will have a White powdery coating. Silicone contamination causes a high but false HO2S signal voltage (rich exhaust indication). The control module will then reduce the amount of fuel delivered to the engine, causing a severe driveability problem. Eliminate the source of contamination before replacing the oxygen sensor. Replace affected HO2S 1. When complete, go to step  13.
  11. Test for poor connections at the PCM. Did you find and correct the condition? If yes, go to step  13. If no, go to next step.
  12. Replace PCM. See POWERTRAIN CONTROL MODULE in appropriate REMOVAL, OVERHAUL & INSTALLATION article. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE REPROGRAMMING  under PROGRAMMING. After replacing PCM, go to next step.
  13. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  14. 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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