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 MANUALSCHEVROLET2009MALIBU LT, 3.5 KREPAIR AND DIAGNOSISELECTRICALINSTRUMENT PANEL SYSTEM DISPLAYS & GAUGESDIAGNOSTIC INFORMATION AND PROCEDURESDTC P0520CIRCUIT/SYSTEM TESTING
2009 Chevrolet Malibu LT, 3.5 K
Circuit/System Testing
2009 Chevrolet Malibu LT, 3.5 KSECTION Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the engine oil pressure (EOP) switch.
- Ignition OFF, test for less than 1 ohm between the low reference circuit terminal B (LY7 only) and ground.
- If greater than the specified value, test the low reference circuit for an open/high resistance.
- Ignition ON, verify the scan tool Engine Oil Pressure Switch parameter is OK.
- If not the specified value, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the ECM.
- Ignition ON, install a 3-amp fused jumper wire between the signal circuit terminal A and ground. Verify the scan tool Engine Oil Pressure Switch parameter is Low.
- If not the specified value, test the signal 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 engine oil pressure switch.
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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.