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 DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 16 (ENGINE CONTROLS - TESTS W/CODES - 5.0L PFI)
1991 Pontiac Firebird Formula, 5.0 F, Standard, M39
Section 16 (Engine Controls - Tests W/Codes - 5.0L PFI)
1991 Pontiac Firebird Formula, 5.0 F, Standard, M39SECTION Section 16 (Engine Controls - Tests W/Codes - 5.0L PFI)
WARNING: This page is about a different car, the 1992 Pontiac Firebird and 1992 Chevrolet Camaro. However, it is still accessible from the selected car via links, so may be relevant.
- Introduction
- Model Identification
- Self-Diagnostic System
- Pcm/BCM Code Charts
- Notes
- Code 13, Open Oxygen (O2) Sensor Circuit
- Code 14, Coolant Temperature Sensor, Signal Voltage Low
- Code 15, Coolant Temperature Sensor, Signal Voltage High
- Code 21, Throttle Position Sensor, Signal Voltage High
- Code 22, Throttle Position Sensor, Signal Voltage Low
- Code 23, Mat Sensor Signal Voltage High
- Code 24, Vehicle Speed Sensor (VSS)
- Code 25, Mat Sensor Signal Voltage Low
- Code 32, EGR System Error
- Code 33, Map Sensor, Signal Voltage High
- Code 34, Map Sensor, Signal Voltage Low
- Code 35, IAC Idle Speed Error, W/O Tech 1
- Code 35, IAC Idle Speed Error, Using Tech I
- Code 42, Est Circuit Open Or Grounded
- Code 43, ESC Error, W/O ESC Module
- Code 44, Lean Exhaust Indication
- Code 45, Rich Exhaust Indication
- Code 46, Vehicle Anti-Theft System
- Code 51, Faulty Prom/Mem-Cal
- Code 52, Faulty Cal-PAK
- Code 54, Fuel Pump Voltage Low
- Code 55, ECM Error
- Summary
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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.