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 MANUALSGEO1991TRACKER LSI, AUTOMATICREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROLS - TESTS W/CODES
1991 Geo Tracker LSi, Automatic
Engine Controls - Tests W/Codes
1991 Geo Tracker LSi, AutomaticSECTION Engine Controls - Tests W/Codes
- Introduction
- Self-Diagnostic System
- Diagnostic Code Charts
- Diagnostic Circuit Check
- Chart A1, No Check Engine Light
- Diagnostic Aids
- Chart A2, Won't Flash Code 12/Check Engine Light On Steady
- Code 13, O2 Sensor CKT/Open CKT
- Code 14, Coolant Temp Sensor CKT/Low Temp Indicated
- Code 15, Coolant Temp Sensor 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 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/Signal Voltage High, Low Vacuum
- Code 32, Map Sensor CKT/Signal Voltage Low, High Vacuum
- Code 41, Ignition Signal CKT/No Signal
- Code 42, Crank Angle Sensor CKT/No Signal For 3 Seconds
- Code 44, Idle Switch CKT/Open CKT Or MISADJUSTED TPS
- Code 45, Idle Switch CKT/CKT Grounded Or MISADJUSTED TPS
- Code 51, EGR System & EGR Temp Sensor (EGRTS) Temp Too Low Or High (CALIF. Only)
- Code 53, Ground CKT Open (CALIF. Only)
- 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.