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Home >> Buick >> 2008 >> Allure CXL >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 7 (Engine Control System & Fuel System - 3.6L - DTC P0008 To DTC P0333) >> DTC P0137, P0138, or P0140 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
  1. Ignition OFF, disconnect the harness connector at the HO2S 2.
  2. Ignition ON, test for 350-550 mV between the high signal circuit terminal B and ground.
    • If less than the specified range, test the high signal circuit for a short to ground, or an open/high resistance. If the circuit tests normal, replace the ECM.
    • If greater than the specified range, test the high signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  3. Connect a 3A fused jumper wire between the high signal circuit terminal B and the low signal circuit terminal A. Verify the scan tool HO2S 2 parameter is less than 10 mV.
    • If greater than the specified range, test the low signal circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  4. If all conditions test normal, replace the HO2S 2.
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