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 MANUALSCHEVROLET1984CAVALIER L4-121 2.0L VIN P TBIREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSTESTING AND INSPECTIONINITIAL INSPECTION AND DIAGNOSTIC OVERVIEWDESCRIPTION OF ON-BOARD DIAGNOSTICSFIELD SERVICE MODE CHECK
1984 Chevrolet Cavalier L4-121 2.0L VIN P TBI
Field Service Mode Check
1984 Chevrolet Cavalier L4-121 2.0L VIN P TBISECTION Field Service Mode Check
1. Ground diagnostic test terminal.
2. Operate engine at 1400-2000 RPM for two minutes and note ``Check Engine'' light.
3. If ``Check Engine'' light flashes approximately one time per second, the fuel system is functioning properly. Refer to ``Erratic or Intermittent Check Engine Light'' in HOW TO RUN TESTS, READ & EXTRACT CODES.
4. If ``Check Engine'' light flashes approximately 21/2 times per second, refer to ``Code 13 Oxygen Sensor Circuit.''
5. If ``Check Engine'' light does not illuminate or only lights infrequently, refer to ``Code 44 Lean Exhaust Indication.''
6. If ``Check Engine'' light stays lit for extended periods, refer to ``Code 45 Rich Exhaust Indication.''
7. If a Code 12 is displayed, refer to ``Crank Signal Circuit Check.''
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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.