Pontiac OBD/OBD2 Codes >> Firebird 5.7L (1993 – 1995)

ModelYearEngine identificationSystem
Firebird  5.7L1993-95VIN  position 8 = PGM

General information

  • Malfunction indicator lamp (MIL) will illuminate if certain faults are recorded.
  • ECM operates in backup mode if sensors fail , to enable vehicle to be driven to repair shop.
  • Trouble codes can be displayed by the MIL or by using a Scan Tool connected to the data link connector (DLC).


  • Access data link connector (DLC).
  • Jump data link connector (DLC) terminals A and B [1].
  • Switch ignition ON. 00 NOT start engine.
  • Count MIL flashes. Note trouble codes. Compare with trouble code table.
  • Firstly trouble code 12 will be displayed 3 times.
  • Trouble codes consist of 2 groups, displayed as follows:
o First group indicates the ‘tens’ of the trouble code [2] [A].
o Second group indicates the ‘units’ of the trouble code [2] [C].
o A short pause separates each group [2] [B].
o A long pause separates each trouble code [2] [D].
o For example: Trouble code 12 displayed [2]. Start of diagnosis.
  • Each additional trouble code will now be displayed 3 times, in ascending order.
NOTE: If no additional trouble codes are stored, code 12 will continue to be displayed.
  • Trouble codes can also be displayed by using a Scan Tool connected to the data link connector (DLC ) [1]


NOTE: Disconnecting battery ground lead may cause driveabi/ity problems until the engine management system relearns basic values.
  • Ensure ignition switched OFF.
  • Disconnect battery ground cable for 30 seconds.
  • Reconnect battery ground cable.
  • Repeat checking procedure to ensure no trouble codes remain in ECM fault memory.
NOTE: Disconnecting battery ground lead may also erase memory from electronic units, such as radio.
  • Trouble codes can also be erased by using a Scan Tool connected to the data link connector (DLC).

Trouble code  identification

Flash codeFault locationProbable cause
11Malfunction indicator lamp (MIL) -circuit malfunctionWiring open circuit/short circuit to ground, MIL, ECM
12Start of diagnosisNo engine speed (RPM) signal received
13Oxygen sensor (02S)/heated oxygen sensor (H02S), bank 1Wiring open circuit, 02S/H02S, ECM
14Engine coolant temperature (ECT) sensor voltage high!lowWiring, ECT sensor, ECM
15Engine coolant temperature (ECT) sensor voltage highWiring open circuit, ECT sensor, ECM
16Distributor ignition system, low resolution signal -circuit malfunctionWiring, distributor, ECM
18Injector(s) -circuit malfunctionWiring, injector(s)
21Throttle position (TP) sensor -voltage high/ lowWiring, TP sensor, ECM
22Throttle position (TP) sensor -voltage lowWiring open circuit/short circuit to ground, TP sensor, ECM
23Intake air temperature (IAT) sensor -voltage high/lowWiring, IAT sensor, ECM
24Vehicle speed sensor (VSS) -no signalWiring, VSS, ECM
25Intake air temperature (IAT) sensor -voltage lowWiring short circuit to ground, IAT sensor, ECM
26Engine control module (ECM), quad driver! output driver -circuit malfunctionWiring, ECM controlled components, ECM III
27Engine control module (ECM), quad driver! output driver -circuit malfunctionWiring, ECM controlled components, ECM III
28 1Engine control module (EGM). quad driver/ output driver -circuit malfunctionWiring, ECM controlled components. ECM 1:1
28 2Transmission gear pressure switch. signal circuit malfunctionWiring open circuit/short circuit to ground,reverse/D1/D2/D3/D4 gear pressure switch(es),ECM
29Secondary air injection (AIR) pump relay circuit malfunctionWiring, AIR pump relay, ECM
32Exhaust gas recirculation (EGR) solenoidWiring, poor connections, EGR valve, ECM
33Manifold absolute pressure (MAP) sensor voltage highllowWiring, hose blockedlleaking, MAP sensor, ECM
34Manifold absolute pressure (MAP) sensor voltage lowWiring open circuit/short circuit to ground, MAP sensor, ECM
36Distributor ignition system. high resolution signal-circuit malfunctionWiring, distributor, ECM
37Brake pedal position (BPP) switch for torque converter clutch (TCC) -high voltageWiring short to positive, incorrectly adjusted, BPP switch, ECM
38Brake pedal position (BPP) switch. torque converter clutch (TCC) -low voltageWiring open circuit, incorrectly adjusted, BPP switch, ECM
41Ignition control. reference signal -circuit malfunctionWiring open circuit. poor connections, ICM. ECM
42Ignition control. reference signal -circuit malfunctionWiring short to ground. ICM, ECM
43Knock sensor (KS) -circuit malfunctionWiring, KS, ECM
44Oxygen sensor (02S)/heated oxygen sensor (H02S). bank 1 mixture leanWiring open circuit/short circuit to ground, injector(s) blocked. fuel contamination. fuel pressure low. exhaust system leaking, 02S/H02S,ECM
45Oxygen sensor (02S)lheated oxygen sensor(H02S). bank 1 -mixture richWiring open circuit, fuel pressure high, injector(s) leaking, 02S/H02S, EVAP purge valve, throttle position (TP) sensor, EGR system, ECM
46Immobilizer system. code -malfunctionIncorrect key, ECM
47Knock control module. removable part in ECM -circuit malfunctionWiring. poor connection, missing knock control module. ECM
48Mass airflow (MAF) sensor -no signalWiring. poor connections, MAF sensor, ECM
50System voltage lowAlternator
51Engine control module (ECM). PROM -malfunctionPoor connections, incorrect programming, ECM
53System voltage highAlternator
55Engine control module (ECM). fuel lean monitorFuel filterllines blocked, fuel contamination
58Transmission fluid temperature (TFT) sensorvoltage lowWiring short circuit to ground, TFT sensor, ECM
59Transmission fluid temperature (TFT) sensorvoltage highWiring open circuit, TFT sensor, ECM
61AlC system -performanceRefrigerant low, wiring, AlC refrigerant pressure sensor, AlC evaporator temperature sensor, ECM
63Oxygen sensor (02S)/heated oxygen sensor(H02S), bank 2Wiring open circuit, 025/H025, ECM
64Oxygen sensor (02S)/heated oxygen sensor (H02S), bank 2 -mixture leanWiring open circuit/short circuit to ground, injector(s) blocked, fuel contamination, fuel pressure low, exhaust system leaking, 025/H025,ECM
65Oxygen sensor (02S)/heated oxygen sensor (H02S), bank 2 -mixture richWiring open circuit, fuel pressure high, injector(s)leaking, 025/H025, EVAP purge valve, throttle position (TP) sensor, EGR system, ECM
66AlC refrigerant pressure sensor -voltage lowWiring open circuit/short circuit to ground, AlC refrigerant pressure sensor, ECM
67AlC refrigerant pressure sensor -circuit malfunctionWiring open circuit, AlC refrigerant pressure sensor, ECM
68AlC compressor clutch relay -circuit malfunctionWiring short circuit, AlC compressor clutch relay, ECM
69AlC compressor clutch relay -circuit malfunctionWiring open circuit, AlC compressor clutch relay, ECM
70AlC compressor clutch relay, control signal -circuit malfunctionWiring, AlC compressor clutch relay, ECM
71AlC evaporator temperature sensor -voltage highWiring, poor connections, AlC evaporator temperature sensor
72Vehicle speed sensor (VSS) -loss of signalWiring, V55, ECM
73Transmission fluid pressure (TFP) controlsolenoid -circuit malfunctionWiring, poor connection, TFP solenoid
74Traction control system (TCS), active signal -malfunctionWiring short to ground, AB5ITC5, ECM
75System voltage low, engine control module (ECM)Wiring, battery, alternator, ECM
77Engine coolant blower motor relay -circuit malfunctionWiring, engine coolant blower motor relay, ECM
79Transmission fluid temperature (TFT) highTransmission mechanical fault, towing weightlimit exceeded
80Torque converter clutch (TCC) -slippingWiring, TCC solenoid, transmission mechanical fault, ECM
81Transmission shift solenoid (SS), 2nd-3rd -circuit malfunctionWiring, 55, ECM
82Transmission shift solenoid (SS), 1st-2nd circuit malfunctionWiring, 55, ECM
83Reverse gear inhibit solenoid -circuit malfunctionWiring, reverse gear inhibit solenoid, ECM
84Transmission 3rd-2nd control solenoid -circuit malfunctionWiringcontrol solenoidECM
84Skip shift solenoid -circuit malfunctionWiringskip shift solenoidECM
85Torque converter clutch (TCC) solenoid -stuckONWiring open circuit/short circuit to ground,transmission internal wiring, TCC solenoid, transmission mechanical faultECM
90Torque converter clutch (TCC) solenoid circuit malfunctionWiring, TCC solenoidECM
91Skip shift warning lamp -circuit malfunctionWiring, skip shift warning lampECM
97Engine control module (ECM), vehicle speed sensor (VSS) output signal -circuit malfunctionWiringpoor connections, ECM
99Engine control module (ECM), tachometer output signal -circuit malfunctionWiring, poor connections, ECM