GM OBD1 Code List (PDF)

Check the GM OBD1 code list to find out what the codes mean on your car.

>> NEXT STEP: https://www.obdadvisor.com/codes/
Visit our site, and type the code in the search box. You will get more information about the code including causes, symptoms, fixes, and repair costs.

Reading and clearing the codes will become easier with a scan tool.
>> READ MORE: https://www.obdadvisor.com/gm-scan-tool-review/
This article shows a helpful in-depth review of the best OBD1 scan tools for your GM. In fact, GM-specific scanners generally perform better than universal ones, simply because they are made specifically for a particular car brand. It helps to exactly diagnose your vehicle and cut the repair cost.

1. GM OBD1 Codes List
CodesMeaning/Fault Location
12No distributor reference pulse (diagnostic test active)
13Oxygen sensor circuit open or no activity
14Engine coolant temp sensor error (high temp indicated)
15Engine coolant temp sensor error (low temp indicated)
16System voltage too low
17Camshaft position sensor error
21Throttle Position sensor error (signal high)
22Throttle position sensor error (signal low)
23Intake air temp sensor error (low temp indicated)
24Vehicle speed sensor error (open circuit or no activity)
25Intake air temp sensor error (high temp indicated)
26Quad Driver Module (QDM A) error
28Auto transmission range pressure switch error
31Waste gate solenoid circuit error
31Gear Position Switch (PRNDL) error
32
Baro sensor circuit error/ EGR circuit error/ MAP sensor signal
open
33MAP sensor circuit error (signal high indicating low vacuum)
34MAP sensor circuit error (signal low indicating high vacuum)
35IAC problem or idle error
36
MAF sensor error/ 24x crankshaft position sensor circuit error/
4T60-E shifting error
37TCC brake switch circuit error
38TCC brake switch circuit error

2. 39Clutch switch circuit error/ Torque converter clutch error
41
Ignition control error/ MEM-CAL error/ Computer Controlled
Ignition Cam Sensor Signal error
42Ignition bypass circuit error
43Knock sensor error
44Oxygen sensor error (lean condition indicated)
45Oxygen sensor error (rich condition indicated)
46Pass-Key II (VATS) system error - circuit out of freq range
47UART (serial data) circuit error
51PROM error/ Incorrect MEM-CAL
52Fuel cal-pak incorrect or missing
53System voltage too high
53Digital EGR Valve solenoid 1 error
54
Fuel pump circuit low voltage/ Digital EGR Valve solenoid 2
error
55ECM error/Digital EGR Valve solenoid 3 error
56Quad Driver Module (QDM B) error
57Boost Control error
58
Trans fluid temp sensor circuit error (low voltage)/ VATS
system error
59Trans fluid temp sensor circuit error (high voltage)
61A/C system performance
63
Right bank O2 sensor circuit error/ MAP sensor circuit signal
voltage high (low vacuum indicated)
64
Right bank O2 sensor lean exhaust indicated/ MAP sensor
circuit signal voltage low (high vacuum indicated)
65Right bank O2 sensor rich exhaust indicated
66A/C pressure sensor circuit error (low pressure indicated)

3. 67A/C pressure sensor circuit error
68A/C clutch relay circuit error (shorted to ground)
69
A/C clutch relay circuit error (open circuit indicated)/ A/C high
pressure switch error
70A/C pressure sensor circuit error (high pressure indicated)
71A/C evaporator temp sensor circuit error (low temp indicated)
72VSS signal circuit error
73A/C evaporator temp sensor circuit error (high temp indicated)
75Digital EGR solenoid #1 circuit error
76Digital EGR solenoid #2 circuit error
77Digital EGR solenoid #3 circuit error
79Transmission fluid over temp
80Transmission component slipping
823x Crankshaft position sensor circuit error
85PROM error
86ECM Analog/Digital error
87EEPROM error (flash memory error)
90TCC error
93Transmission pressure control solenoid circuit error
96Transmission system voltage low
98Invalid PCM program
99Invalid PCM program