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 P0135 OR P0141CIRCUIT/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 appropriate H02S.
- Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit terminal 2 and ground.
- If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition 1 voltage circuit fuse is open, test all components connected to the ignition 1 voltage circuit and replace as necessary.
IMPORTANT: The ignition 1 voltage circuit supplies voltage to other components. Make sure you test all circuits for a short to ground or test all components for being shorted that share the ignition 1 voltage circuit. - Ignition OFF, connect a test lamp between the control circuit terminal 3 and B+. The test lamp should not illuminate.
- If test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.
- Engine running, verify the test lamp illuminates or flashes.
- If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
- If all circuits test normal, test or replace the H02S 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.