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.
1991 Pontiac LeMans BaseFACTORY OEM SERVICE PROCEDURE
Engine Controls - Tests W/Codes
- Introduction
- Self-Diagnostic System
- Diagnostic Circuit Check
- Diagnostic Charts
- Diagnostic Code Charts
- Code 13, Open Oxygen Sensor Circuit
- Code 14, Coolant Temp Sensor (Temperature Too High)
- Code 15, Coolant Temp Sensor (Temperature Too Low)
- Code 21, Throttle Position Sensor (Signal Voltage High)
- Code 22, Throttle Position Sensor (Signal Voltage Low)
- Code 24, Vehicle Speed Sensor
- Code 32, EGR System Error
- Code 33, Map Sensor (Signal Voltage High/Low Vacuum)
- Code 34, Map Sensor (Signal Voltage Low/High Vacuum)
- Code 42, Electronic Spark Timing (Est) Circuit
- Code 44, Oxygen (O2) Sensor Circuit (Lean Exhaust Indication)
- Code 45, Oxygen (O2) Sensor CKT, (Rich Exhaust Indication)
- Code 51, Faulty Mem-Cal
- Code 53, System OVERVOLTAGE
- Summary
Factory Service Tools
Use the Manual With the Right Hardware
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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.
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