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.
1992 Geo Metro Base, 2D Hatchback, AutomaticFACTORY OEM SERVICE PROCEDURE
Engine Controls - Tests W/Codes
- Introduction
- Self-Diagnostic System
- Summary
- Diagnostic Code Charts
- Notes
- Diagnostic Circuit Check
- Chart A-1, No "Check Engine" Light
- Chart A-2, Won't Flash Code 12/Check Engine Light On Steady
- Code 13, Oxygen Sensor Circuit, Signal Voltage Doesn't Change
- Code 14, Coolant Temp Sensor (Cts) CKT, Low Temp. Indicated
- Code 15, Coolant Temp Sensor (Cts) CKT, High Temp Indicated
- Code 21, Throttle Position Sensor CKT, Signal Voltage High
- Code 22, Throttle Position Sensor CKT, Signal Voltage Low
- CODE 23, INTAKE AIR TEMP (IAT) SENSOR CkT, LOW TEMP INDICATED
- Code 24, Vehicle Speed Sensor Circuit
- Code 25, Intake Air Temp Sensor CKT, High Temp Indicated
- Code 31, Map Sensor CKT, Low Voltage Input - Low Vacuum
- Code 32, Map Sensor Circuit, High Voltage Input - High Vacuum
- Code 41, Ignition Signal Circuit, No Signal
- Code 42, Crank Angle Sensor Circuit, No Signal For 3 Seconds
- Code 51, Exhaust Gas RECIRCULATION (EGR) Circuit
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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