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 MANUALSOLDSMOBILE1987FIRENZA BASE, 4D SEDAN, 2.0 K, AUTOMATICREPAIR AND DIAGNOSISENGINE PERFORMANCESYSTEM2.0L VIN [K] / 2.5L VINS [R & U] TESTS W/CODESDIAGNOSTIC CHARTSCODE 13 - OPEN OXYGEN (O2) SENSOR CKT (A/J/N/P BODY)DIAGNOSTIC AIDS

1987 Oldsmobile Firenza Base, 4D Sedan, 2.0 K, Automatic

Diagnostic Aids

1987 Oldsmobile Firenza Base, 4D Sedan, 2.0 K, AutomaticSECTION Diagnostic Aids

Verify a clean, tight ground connection for circuit No. 413. An open circuit at terminal No. 412 or No. 413 will result in a Code 13.

Fig 1: Code 13 Schematic: Open O2 Sensor Circuit (A/J/N/P Body)

G50H06656

RENDER: 1.0x

NO RELATED

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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.