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.
1990 Geo Metro LSi, 2D Convertible, AutomaticFACTORY OEM SERVICE PROCEDURE
Engine Controls - Tests W/Codes
- Introduction
- Self-Diagnostic System
- Metro Code Charts
- Chart A-1, No Check Engine Light
- Chart A-2, Won't Flash Code 12
- Code 13, Oxygen Sensor Circuit Open Circuit
- Code 14, Coolant Temperature Sensor (Cts) Circuit High Temperature Indicated
- Code 15, Coolant Temperature Sensor (Cts) Circuit Low Temperature Indicated
- Code 21, Throttle Switch Circuit (M/T Only) Both Idle Switch Wide Open Throttle Switch Indicated On
- Code 21, Throttle Position Sensor (TPS) Circuit (A/T Only) Signal Voltage High
- Code 22, Throttle Position Sensor (TPS) Circuit (A/T Only) Signal Voltage Low
- Code 23, Manifold Air Temperature (Mat) Sensor Circuit Low Temperature Indicated
- Code 24, Vehicle Speed Sensor Circuit
- Code 25, Manifold Air Temperature (Mat) Sensor Circuit High Temperature Indicated
- Code 31, Manifold Absolute Pressure (Map) Sensor Circuit Signal Voltage Low With High Vacuum
- Code 32, Manifold Absolute Pressure (Map) Sensor Circuit Signal Voltage High With Low Vacuum
- CODE 41, IGNITION SIGNAL CIRCUIT NO SIGNAL LSi CONVENTIONAL IGNITION SYSTEM
- Code 41, Ignition Signal Circuit No Signal ESA Ignition System
- Code 42, Crank Angle Sensor Circuit No Signal For 2 Seconds
- Code 51, Exhaust Gas RECIRCULATION (EGR) Circuit CALIFORNIA Only)
- 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.