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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 83 (Engine Controls Self-Diagnostics - 2.2L) >> Diagnostic Tests >> DTC P1133: Ho2S Insufficient Switching (Bank 1; Sensor 1) >> Test Description

Test Description

WARNING: This page is about a different car, the 2002 GMC Sonoma and 2002 Chevrolet S10 Pickup. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic procedures.

  1. 2

    This step tests for proper sensor activity. When in Closed Loop fuel control the Heated Oxygen Sensor (HO2S) voltage should rapidly swing above and below the bias voltage.

  2. 4

    This step tests the PCM and the high and low signal circuits between the PCM and the HO2S connector for proper operation.

  3. 7

    This step tests for proper HO2S heater circuit operation up to the HO2S connector.

  4. 8

    This step tests for proper circuit resistance between the HO2S low signal circuit and PCM ground.

  5. 11

    Probable causes include the following: poor O2S low terminal contact at PCM, poor PCM ground connection, high PCM ground circuit resistance and an ungrounded exhaust system.
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