Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2008OPTRA5 LT, STANDARDREPAIR AND DIAGNOSISENGINE PERFORMANCESYSTEMENGINE CONTROLS AND FUEL - 1.6LDIAGNOSTIC INFORMATION AND PROCEDURESDTC P0117 OR P0118CIRCUIT/SYSTEM TESTING
2008 Chevrolet Optra5 LT, Standard
Circuit/System Testing
2008 Chevrolet Optra5 LT, StandardSECTION Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the ECT sensor.
- Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal 1 and ground.
- If less than the specified range, test the signal circuit for a short to ground or an open. If the circuit tests normal, replace the ECM.
- If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
IMPORTANT: If the signal circuit is shorted to voltage the sensor may be damaged. - Test for less than 0.5 volt between the low reference circuit terminal 2 and ground.
- If greater than the specified range, test the low reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
- Install a 3A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2. Verify the ECT sensor parameter is greater than 128°C (262°F).
- If less than the specified range, test the signal circuit and the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
- If all circuits test normal, test or replace the ECT sensor.
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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.