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Home › Chevrolet › 2007 › Optra LS, Standard › Repair and Diagnosis › Engine Performance › System › Engine Controls And Fuel - 1.8L (LDA) › Diagnostic Information and Procedures › DTC P0117 or P0118 › Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the ECT sensor.
  2. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit and ground.
    • If greater than 5 ohms, 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, using a scan tool verify that the ECT sensor parameter is at -40°C (-40°F).
    • If greater than -40°C (-40°F), test the signal circuit of the ECT sensor for a short to ground. If the circuit tests normal, replace the engine control module (ECM).
    4. IMPORTANT: If the signal circuit of the ECT sensor is shorted to voltage the ECT sensor may be damaged.
  4. Install a 3-amp fused jumper wire between the signal circuit and the low reference circuit. Verify the ECT sensor parameter is greater than 128°C (262°F).
    • If less than 128°C (262°F), test the signal circuit of the ECT sensor for a short to voltage or an open/high resistance. If the circuit test normal, replace the ECM.
  5. If all circuits test normal, test or replace the ECT sensor.
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