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Home >> Chevrolet >> 2008 >> Optra LS, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls And Fuel - 1.6L >> Diagnostic Information and Procedures >> DTC P0131 or P0137 >> Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the HO2S.
  2. Ignition ON, test for less than 0.1 volt between the low reference circuit terminal 1 and ground.
    • If greater than the specified range, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
  3. Ignition ON, verify the scan tool HO2S parameter is between 350-500 mV.
    • If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.
  4. Install a 3A fused jumper wire between the signal circuit terminal 4 and the low reference circuit terminal 1. Verify the scan tool HO2S sensor parameter is less than 60 mV.
    • If greater than the specified range, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  5. Verify the following conditions do not exist:
    • If you find any of the above conditions, repair as necessary.
  6. If all circuits test normal, test or replace the applicable HO2S.
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