Retrieval of OBD1 Codes (Vehicles Manufactured Prior to 1995)
Self-retrieval of OBD1 codes for GM cars from 1983 to 1995
The designation indicates that owners of GM vehicles manufactured before to 1995 may independently get diagnostic codes. Consequently, upon activation of the "check engine light," one can obtain the code within minutes if desired.
Displayed on the left is an image of the connection used for retrieving the GM OBD1 code.
Upon locating the adapter connection, using a jumper wire (refer to the red wire above) to connect terminals A and B. Next, turn the key to the 'on' position without starting the engine. Observe the check engine light display the code(s).
INSTANCE: CODE 12: one prolonged flash and two brief flashesCODE 13: one prolonged flash and three brief flashes.
Note: Code 12 is often the first code received and should be disregarded.Examine the code subsequent to code 12; that is what you want.
General Motors standard codes for OBD1 (for cars manufactured before to 1995)
System normal at 12
Oxygen sensor circuit malfunction: open circuit detected
14 coolant sensor exhibiting elevated resistance or short circuit
15 coolant sensor circuit low or open
Fault in circuit of the 16 direct ignition system (DIS)
Fault in the cam position sensor 17
Error in crank or cam sensor 18
Fault in the crank sensor circuit 19
21 TPS sensor exceeds permissible range
Low voltage indication from the 22 TPS sensor
Intake air temperature sensor 23 is out of range, indicating a low reading.
Fault in the vehicle speed sensor circuit (VSS)
25 air temperature sensor out of range, elevated
Fault in circuit #1 of the 26 quad-driver module (computer)
27 quad-driver module (computer) second gear circuit
Fault in circuit #2 of the 28 quad-driver module (computer)
29 quad driver module (computer) fourth gear circuit
Fault in the cam position sensor 31
Fault in the EGR circuit 32
33 map sensor signal exceeds permissible range, elevated
34 map sensor signal is below the acceptable range.
35 idling air control sensor circuit malfunction
36 ignition system circuit malfunction
Fault in the brake input circuit 38
Fault in the clutch input circuit 39
problem in the cam sensor circuit; problem in the ignition control circuit.
Grounded electronic spark timing (EST) circuit 42
Fault in the knock sensor or electronic spark control circuit
Oxygen sensor indicating a lean exhaust condition
Oxygen sensor indicating excessive richness in exhaust
Fault in the 46 pass-key II circuit or pressure switch circuit.
47 PCM-BCM data circuit
Diagnosis of 48 Misfires
Calibration error 51, memory calibration, ECM or EEPROM failure
Engine oil temperature circuit 52, low temperature detected
53 battery voltage mistake or EGR or Pass-Key II circuit
Failure of the EGR system or low voltage in the fuel pump circuit
55 A/D converter fault, PCM not grounded, low fuel, or grounded reference voltage.
56 quad-driver module number two circuit
Issue with boost control 57
58 car anti-theft system fuel activation circuit
61 A/C system performance or compromised oxygen sensor signal. 62 Elevated engine oil temperature indicated.
63 oxygen sensor right side circuit open or manifold absolute pressure sensor out of range
Oxygen sensor on the right side indicates a lean exhaust condition.
Oxygen sensor on the right side indicates a rich exhaust condition.
66 air conditioning pressure sensor circuit low pressure
Failure of the A/C pressure sensor circuit or A/C clutch circuit
Failure of the 68 air conditioning compressor relay circuit
69 A/C clutch circuit exhibits elevated head pressure.
70 A/C refrigerant pressure circuit elevated
71 A/C evaporator temperature sensor circuit malfunction: low voltage
72 gear selector switch circuitry
73 A/C evaporator temperature circuit elevated
75 Digital EGR #1 solenoid malfunction 76 Digital EGR #2 solenoid malfunction 77 Digital EGR #3 solenoid malfunction 79 Vehicle speed sensor (VSS) circuit signal elevated 80 Vehicle speed sensor (VSS) circuit signal diminished 81 Brake input circuit anomaly 82 Ignition control (IC) 3X signal malfunction 85 PROM malfunction 86 Analog/digital ECM malfunction 87 EEPROM malfunction 99 Power management issue
Self-retrieval of OBD1 codes for GM cars from 1983 to 1995
The designation indicates that owners of GM vehicles manufactured before to 1995 may independently get diagnostic codes. Consequently, upon activation of the "check engine light," one can obtain the code within minutes if desired.
Displayed on the left is an image of the connection used for retrieving the GM OBD1 code.
Upon locating the adapter connection, using a jumper wire (refer to the red wire above) to connect terminals A and B. Next, turn the key to the 'on' position without starting the engine. Observe the check engine light display the code(s).
INSTANCE: CODE 12: one prolonged flash and two brief flashesCODE 13: one prolonged flash and three brief flashes.
Note: Code 12 is often the first code received and should be disregarded.Examine the code subsequent to code 12; that is what you want.
General Motors standard codes for OBD1 (for cars manufactured before to 1995)
System normal at 12
Oxygen sensor circuit malfunction: open circuit detected
14 coolant sensor exhibiting elevated resistance or short circuit
15 coolant sensor circuit low or open
Fault in circuit of the 16 direct ignition system (DIS)
Fault in the cam position sensor 17
Error in crank or cam sensor 18
Fault in the crank sensor circuit 19
21 TPS sensor exceeds permissible range
Low voltage indication from the 22 TPS sensor
Intake air temperature sensor 23 is out of range, indicating a low reading.
Fault in the vehicle speed sensor circuit (VSS)
25 air temperature sensor out of range, elevated
Fault in circuit #1 of the 26 quad-driver module (computer)
27 quad-driver module (computer) second gear circuit
Fault in circuit #2 of the 28 quad-driver module (computer)
29 quad driver module (computer) fourth gear circuit
Fault in the cam position sensor 31
Fault in the EGR circuit 32
33 map sensor signal exceeds permissible range, elevated
34 map sensor signal is below the acceptable range.
35 idling air control sensor circuit malfunction
36 ignition system circuit malfunction
Fault in the brake input circuit 38
Fault in the clutch input circuit 39
problem in the cam sensor circuit; problem in the ignition control circuit.
Grounded electronic spark timing (EST) circuit 42
Fault in the knock sensor or electronic spark control circuit
Oxygen sensor indicating a lean exhaust condition
Oxygen sensor indicating excessive richness in exhaust
Fault in the 46 pass-key II circuit or pressure switch circuit.
47 PCM-BCM data circuit
Diagnosis of 48 Misfires
Calibration error 51, memory calibration, ECM or EEPROM failure
Engine oil temperature circuit 52, low temperature detected
53 battery voltage mistake or EGR or Pass-Key II circuit
Failure of the EGR system or low voltage in the fuel pump circuit
55 A/D converter fault, PCM not grounded, low fuel, or grounded reference voltage.
56 quad-driver module number two circuit
Issue with boost control 57
58 car anti-theft system fuel activation circuit
61 A/C system performance or compromised oxygen sensor signal. 62 Elevated engine oil temperature indicated.
63 oxygen sensor right side circuit open or manifold absolute pressure sensor out of range
Oxygen sensor on the right side indicates a lean exhaust condition.
Oxygen sensor on the right side indicates a rich exhaust condition.
66 air conditioning pressure sensor circuit low pressure
Failure of the A/C pressure sensor circuit or A/C clutch circuit
Failure of the 68 air conditioning compressor relay circuit
69 A/C clutch circuit exhibits elevated head pressure.
70 A/C refrigerant pressure circuit elevated
71 A/C evaporator temperature sensor circuit malfunction: low voltage
72 gear selector switch circuitry
73 A/C evaporator temperature circuit elevated
75 Digital EGR #1 solenoid malfunction 76 Digital EGR #2 solenoid malfunction 77 Digital EGR #3 solenoid malfunction 79 Vehicle speed sensor (VSS) circuit signal elevated 80 Vehicle speed sensor (VSS) circuit signal diminished 81 Brake input circuit anomaly 82 Ignition control (IC) 3X signal malfunction 85 PROM malfunction 86 Analog/digital ECM malfunction 87 EEPROM malfunction 99 Power management issue