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 MANUALSPONTIAC1991SUNBIRD BASE, 4D SEDAN, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS - TESTS W/CODES - 3.1L PFI
1991 Pontiac Sunbird Base, 4D Sedan, Standard
Engine Controls - Tests W/Codes - 3.1L PFI
1991 Pontiac Sunbird Base, 4D Sedan, StandardSECTION Engine Controls - Tests W/Codes - 3.1L PFI
- Introduction
- Self-Diagnostic System
- Notes
- Hard Failures
- Intermittent Failures
- Diagnostic Procedure
- Retrieving Codes (Non-Scan)
- Reading Trouble Codes
- Trouble Code Definition
- Hard Or Intermittent Trouble Code Determination
- Clearing Trouble Codes
- ECM/Pcm Location
- Diagnostic Materials
- Special Tools (Diagnostic)
- Scan Tester Usage
- Scan Data
- Test Procedure Summary
- Diagnostic Flow Charts For Codes: 13 To 66
- Notes
- Code 13, Open Oxygen 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, A, F, J, L & W Bodies, EGR System Error
- Code 33, Map Sensor Signal Voltage High
- Code 34, Map Sensor Signal Voltage Low
- Code 35, IAC Idle Speed Error
- Code 35, IAC Idle Speed Error Using Tech I
- Code 41, Cylinder Select Error
- Code 42, Est Circuit Open Or Grounded
- Code 43, ESC Error Without ESC Module
- Code 44, Lean Exhaust Indication
- Code 45, Rich Exhaust Indication
- Code 46, F Body, Vehicle Anti-Theft System
- Code 47, Pcm-BCM Data Loss
- Code 51, Faulty Prom/Mem-Cal
- Code 52, Faulty CALPAK
- Code 53, System OVERVOLTAGE
- Code 54, A, F, J & L Bodies, Fuel Pump Voltage Low
- Code 54, Fuel Pump Voltage Low
- Code EO51, Faulty Prom/Mem-Cal
- Code 61, Degraded Oxygen Sensor
- Code 62, A, J, L & W Bodies Gear Switch Error
- Code 66, J, L & W Bodies A/C Pressure Sensor
- Wiring Diagrams
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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.