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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 102 (Engine Controls - Self-Diagnostics - 3.5L) >> Diagnostic Tests >> DTC P0133: Ho2S Slow Response >> Test Description

Test Description

WARNING: This page is about a different car, the 2002 Oldsmobile Intrigue and 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step number in the diagnostic procedures.

  1. 2

    HO2S contamination may cause multiple HO2S DTCs to set.

  2. 4

    The use of leaded fuel may be indicated by the removal or tampering of the fuel filler restrictor. An HO2S contaminated by silicone will have a White, powdery deposit on the portion of the HO2S that is exposed to exhaust stream. The usual cause of silica contamination is the use of unapproved silicone RTV engine gasket material, the use of silicone based sprays or fluids within the engine or coolant consumption. Phosphorus contamination also leaves a White powdery coating on the HO2S. Phosphorus contamination comes from oil consumption. If the cause of this contamination is not corrected, the replacement HO2S will also get contaminated.

  3. 7

    Even small exhaust leaks can cause slow response from HO2S.

  4. 12

    An HO2S contaminated by silicone will have a White, powdery deposit on the portion of the HO2S that is exposed to the exhaust stream. The usual cause of silica contamination is the use of un-approved silicone RTV engine gasket material, the use of silicone based sprays or fluids within the engine or coolant consumption. Phosphorus contamination also leaves a White powdery coating on the HO2S. Phosphorus contamination comes from oil consumption. If the cause of this contamination is not corrected, the replacement HO2S will also get contaminated.

  5. 13

    If voltage observed in step  8 is less than the range specified, a short between the high and low circuits, or a short between the high circuit and ground is indicated. With HO2S and PCM disconnected, the resistance between the high and low circuits and resistance between the high circuit and ground should measure infinite.

    If voltage observed in step  8 is more than the range specified, a short between the high circuit and an ignition voltage source is indicated.

  6. 14

    If voltage observed in step  9 is not below the voltage specified, a high resistance (open) high or low circuit is indicated. Good circuit continuity measures less than 5 ohms with the PCM and sensor disconnected. Measure between the PCM connector and the HO2S connector. Ensure PCM terminal contact is good.
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