Pontiac OBD/OBD2 Codes >> Bonneville 3.8L – Grand AM 3.3L – Trans Sport 3.8L (1992 – 1993)

ModelYearEngine identificationSystem
Bonneville 3.8L1992-93VIN  position 8 = LGM
Grand AM  3.3L1992-93VIN  position 8 = NGM
Trans Sport 3.8L1992-93VIN  position 8 =  LGM

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. Do 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:
* First group indicates the ‘tens’ of the trouble code [2] [A].
* Second group indicates the ‘units’ of the trouble code [2] [C].
* A short pause separates each group [2] [B].
* A long pause separates each trouble code [2] [D] .
* 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) 1.

Trouble code  identification

Flash codeFault locationProbable cause
12Start of diagnosisNo engine speed (RPM) signal received
13Oxygen sensor (02S)/heated oxygen sensor (H02S)Wiring open Circuit, 02S/H02S, ECM
14Engine coolant temperature (ECT) sensor voltage lowWiring short circuit to ground, ECT sensor, ECM
15Engine coolant temperature (ECT) sensor voltage highWiring open circuit, ECT sensor, ECM
16System voltage high/lowWiring, battery, alternator
17Ignition control system, spark reference signal circuit malfunctionWiring, ICM, ECM
18Camshaft position (CMP) sensor -circuit malfunctionWiring, CMP sensor, mechanical fault, ECM
21Throttle position (TP) sensor -voltage highWiring open circuit/short circuit to positive, TP sensor, ECM
22Throttle position (TP) sensor -voltage lowWiring open circuit/short circuit to ground, TP sensor, ECM
23Intake air temperature (IAT) sensor -voltage highWiring open circuit, 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 0
27Transmission gear switch, signal -circuit malfunctionWiring open circuit/short circuit to ground, 2nd gear switch, 3rd gear switch, ECM
28Transmission gear switch, signal -circuit malfunctionWiring open circuit/short circuit to ground, 2nd gear switch, 3rd gear switch, ECM
31Park/neutral position (PNP) switch -malfunctionWiring, PNP switch, ECM
34Mass airflow (MAF) sensor -voltage lowWiring, poor connections, MAF sensor, ECM
36Transmission shift solenoid (SS) -circuit malfunctionWiring, 55, ECM
38Brake pedal pOSition (BPP) switch, torque converter clutch (TCC)Wiring, incorrectly adjusted, BPP switch, ECM
39Torque converter clutch (TCC) -slippingWiring, TCC solenoid, transmission mechanical fault, ECM
41Camshaft position (CMP) sensor -circuit malfunctionWiring, CMP sensor, mechanical fault, ECM
42Ignition control, timing signal -circuit malfunctionWiring, poor connections, ICM, ECM
43Knock sensor (K8) -circuit malfunctionWiring, KS, ECM
44Oxygen sensor (028)/heated oxygen sensor (H028) -mixture leanWiring open circuit/short circuit to ground, injector(s) blocked, fuel contamination, fuelpressure low, exhaust system leaking, 025/H025,ECM
45_Oxygen sensor (028)/heated oxygen sensor (H028) -mixture richWiring open circuit, fuel pressure high, injector(s) leaking, 025/H025, EVAP purge valve, throttle position (TP) sensor, EGR system, ECM
48Misfire detectedIgnition system, fuel system, 025, engine mechanical fault
51Engine control module (ECM), PROM malfunctionPoor connections, incorrect programming, ECM
53Exhaust gas recirculation (EGR) solenoid 1 circuit malfunctionWiring, EGR valve, ECM
54Exhaust gas recirculation (EGR) solenoid 2 circuit malfunctionWiring, EGR valve, ECM
55Exhaust gas recirculation (EGR) solenoid 3 circuit malfunctionWiring, EGR valve, ECM
56Engine control module (ECM), quad driver/output driver -circuit malfunctionWiring, ECM controlled components, ECM 0
61Cruise control, vent solenoid -circuit malfunctionWiring, solenoid valve
62Cruise control, vacuum solenoid -circuit malfunctionWiring, solenoid valve
63Cruise control system -performance lowWiring, poor connections, accelerator cable sticking
65Cruise control servo position sensor -circuit malfunctionWiring, poor connections, servo position sensor
66AlC refrigerant pressure sensor -voltage lowIncorrect refrigerant charge, wiring, AlC refrigerant pressure sensor, ECM
67Cruise control master switch -circuit malfunctionWiring, poor connections, cruise control master switch
68Cruise control system -performance highWiring, poor connections, accelerator cable sticking
69AlC refrigerant pressure switch, engine coolant blower motors -circuit malfunctionWiring open circuit, AlC refrigerant pressure switch,ECM
99Cruise control system -engine management has operated in limited power modeAccelerator cable sticking, brake vacuum release valve, cruise control actuator
[1] Depending on model, year and equipment level, the following components may be connected to this circuit. Use of the vehicle wiring diagram is recommended to confirm which components are fitted.
o A/C compressor clutch relay0Exhaust gas recirculation (EGR) solenoid
o A/C condenser blower motor relay0Malfunction indicator lamp (MIL)
o Engine coolant blower motor relay0Torque converter clutch (TCC) solenoid
o Engine coolant ‘hot’ warning lamp0Transmission shift solenoids (88)
o Evaporative emission (EVAP) canister purge0Transmission shift warning lamp (MT)