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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 258 (Engine Controls Self-Diagnostics - 2.2L) >> Diagnostic Tests >> DTC P1133: Ho2S Insufficient Switching (Bank 1; Sensor 1) >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2003 GMC Sonoma and 2003 Chevrolet S10 Pickup. 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, 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.
  2. With engine at operating temperature. Operate engine at greater than 1200 RPM for 2 minutes. With scan tool, observe the O2 voltage parameter. Does the scan tool indicate O2 voltage varying outside 400-500 mV range? If yes, go to next step. If no, go to step  4 .
  3. Observe the Freeze Frame/Failure Records for this DTC. Turn OFF the ignition 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, see DIAGNOSTIC AIDS  .
  4. Inspect and test for exhaust leak, properly installed O2S or damaged wiring. Did you find and correct the condition? If yes, go to step  13 . If no, go to next step.
  5. Turn ignition off. Disconnect O2S harness connector. Turn ignition on. Measure the voltage on the O2S high signal circuit, PCM side, using a DVOM that is connected to a good ground. Does the voltage measure about 450 mV? 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 O2S voltage parameter. Does the scan tool indicate O2S voltage at or about zero mV? If yes, go to step  9 . If no, go to next step.
  7. Test the low signal circuit for an open or high resistance. 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. Did you find and correct the condition? If yes, go to step  13 . If no, go to step  11 .
  9. Test for poor connections at the O2S. 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 use of improper RTV sealant. Contamination of the oxygen sensor can result from the use of an inappropriate RTV sealant (not oxygen sensor safe) or excessive engine coolant or oil consumption. Remove 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. After repairs and replacing sensor, 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 appropriate REMOVAL & INSTALLATION article. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After replacing PCM, go to next step.
  13. Clear DTCs with scan tool. Turn OFF the ignition for 30 seconds. Operate 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 step  2 . If no, go to next step.
  14. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? If yes, diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no, system is okay.
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