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 MANUALSPONTIAC1991FIREBIRD FORMULA, 5.0 F, STANDARD, M39REPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS - TESTS W/CODES - 5.0L PFIDIAGNOSTIC FLOW CHARTS FOR CODES: 13 TO 69CODE 42, EST CIRCUIT OPEN OR GROUNDEDDIAGNOSTIC AIDS
1991 Pontiac Firebird Formula, 5.0 F, Standard, M39
Diagnostic Aids
1991 Pontiac Firebird Formula, 5.0 F, Standard, M39SECTION Diagnostic Aids
The "Scan" tester does not have the ability to help diagnose a Code 42 problem. See INTERMITTENTS in TESTS W/O CODES article in this section.
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.