2007 Chevrolet Optra5 LS, AutomaticFACTORY OEM SERVICE PROCEDURE

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector of the IAT sensor.
    2. IMPORTANT: The DTCs must be cleared or a temperature of 20°C (68°F) will be displayed on the scan tool.
  2. Ignition ON, verify that the IAT sensor parameter is at -40°C (-40°F).
    • If greater than -40°C (-40°F), test the signal circuit of the IAT sensor for a short to ground. If the circuit/connections test normal, replace the engine control module (ECM).
  3. Test for less than 0.5 volt between the low reference circuit of the IAT sensor and the negative terminal of the battery.
    • If greater than 0.5 volt, test the low reference circuit of the IAT sensor for a short to voltage. If the circuit/connections test normal, replace the ECM.
  4. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit of the IAT sensor and the negative terminal of the battery.
    • If greater than 5 ohms, test the low reference circuit of the IAT sensor for an open/high resistance. If the circuit/connections test normal, replace the ECM.
    5. IMPORTANT: The DTCs must be cleared or a temperature of 20°C (68°F) will be displayed on the scan tool.
  5. Install a 3-amp fused jumper wire between the signal circuit and the low reference circuit of the IAT sensor and verify the IAT sensor parameter is greater than 128°C (262°F).
    • If less than 128°C (262°F), test the signal circuit of the IAT sensor for a short to voltage or an open/high resistance. If the circuit/connections test normal, replace the ECM.
  6. If all circuits/connections test normal, test or replace the IAT sensor.
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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