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 MANUALSPONTIAC1987FIREBIRD FORMULA, 5.0 H, AUTOMATICREPAIR AND DIAGNOSISENGINE PERFORMANCESYSTEM5.0L FEEDBACK CARBURETOR TESTS W/CODESECM TROUBLE CODE DEFINITIONS
1987 Pontiac Firebird Formula, 5.0 H, Automatic
ECM Trouble Code Definitions
1987 Pontiac Firebird Formula, 5.0 H, AutomaticSECTION ECM Trouble Code Definitions
ECM TROUBLE CODE DEFINITION
| Code No. | Circuit Affected | ||
|---|---|---|---|
| 12 (1) | No RPM reference pulse | ||
| 13 | Open oxygen sensor circuit | ||
| 14 | Coolant sensor circuit shorted | ||
| 15 | Coolant sensor circuit open | ||
| 21 | TPS signal voltage high | ||
| 22 | TPS signal voltage low | ||
| 23 | MAT voltage high | ||
| 23 | M/C solenoid voltage low | ||
| 24 | VSS circuit | ||
| 25 | MAT sensor signal voltage low | ||
| 31 | Purge sol. voltage high (carb.) | ||
| 32 | EGR vacuum control signal | ||
| 32 | BARO voltage low (carb.) | ||
| 33 | MAP sensor voltage high | ||
| 33 | MAF sensor frequency high (PFI) | ||
| 34 | MAP sensor voltage low | ||
| 34 | VAC sensor circuit | ||
| 34 | MAF sensor frequency low (PFI) | ||
| 35 | IAC (EFI) or ISC (carb.) speed error | ||
| 36 | MAF sensor burnoff | ||
| 41 | No distributor reference (HEI) | ||
| 41 | C(3)I ignition - cam sensor loss | ||
| 41 | Cylinder select error (MEM-CAL) | ||
| 42 | EST circuit open or grounded | ||
| 43 | ESC retard signal too low | ||
| 44 | Lean oxygen sensor value | ||
| 45 | Rich oxygen sensor value | ||
| 51 | Faulty PROM, MEM-CAL or ECM | ||
| 52 | Faulty/missing CALPAC or MEM-CAL | ||
| 53 | Faulty alternator, voltage high | ||
| 54 | Fuel pump voltage low | ||
| 55 | Faulty ECM | ||
|
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NOTE:
Trouble code charts should only be used if "SERVICE ENGINE SOON" light is illuminated (indicating a current problem exists). Exceptions are Code 13, 15, 24, 44 and 45 charts, which may be used to help diagnose intermittent codes.
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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.