GM OBD-1 Diagnostic Trouble Codes

For 1995-previous model year EFI-equipped GM vehicles. NOTE: Some codes not supported on all models, consult your specific vehicle's service manual for the correct trouble code list and description for your application.

DTC - 12 No distributor reference pulse (diagnostic test active)

DTC - 13 Oxygen sensor circuit open or no activity

DTC - 13 Left bank O2 sensor circuit open or no activity

DTC - 14 Engine coolant temp sensor error (high temp indicated)

DTC - 15 Engine coolant temp sensor error (low temp indicated)

DTC - 16 System voltage too low

DTC - 17 Camshaft position sensor error

DTC - 21 Throttle Position sensor error (signal high)

DTC - 22 Throttle position sensor error (signal low)

DTC - 23 Intake air temp sensor error (low temp indicated)

DTC - 24 Vehicle speed sensor error (open circuit or no activity)

DTC - 25 Intake air temp sensor error (high temp indicated)

DTC - 26 Quad Driver Module (QDM A) error

DTC - 28 Auto transmission range pressure switch error

DTC - 31 Wastegate solenoid circuit error

DTC - 31 Gear Position Switch (PRNDL) error

DTC - 32 EGR system failure

DTC - 33 MAP sensor circuit error (signal high indicating low vacuum)

DTC - 34 MAP sensor circuit error (signal low indicating high vacuum)

DTC - 35 IAC problem or idle error

DTC - 36 MAF sensor error

DTC - 36 24x Crankshaft position sensor circuit error

DTC - 36 4T60-E Shifting Error

DTC - 37 TCC brake switch circuit error

DTC - 38 TCC brake switch circuit error

DTC - 39 Clutch switch circuit error

DTC - 39 TCC error

DTC - 41 Ignition control error

DTC - 41 MEM-CAL error

DTC - 41 C³I Cam Sensor Signal error

DTC - 42 Ignition bypass circuit error

DTC - 43 Knock sensor error

DTC - 44 Oxygen sensor error (lean condition indicated)

DTC - 44 Left bank O2 sensor error (lean condition indicated)

DTC - 45 Oxygen sensor error (rich condition indicated)

DTC - 45 Left bank O2 sensor error (rich condition indicated)

DTC - 46 Pass-Key II (VATS) system error - circuit out of freq range

DTC - 47 UART (serial data) circuit error

DTC - 51 PROM error

DTC - 51 Incorrect MEM-CAL

DTC - 52 Fuel cal-pak incorrect or missing

DTC - 53 System voltage too high

DTC - 53 Digital EGR Valve solenoid 1 error

DTC - 54 Fuel pump circuit low voltage

DTC - 54 Digital EGR Valve solenoid 2 error

DTC - 55 ECM error

DTC - 55 Digital EGR Valve solenoid 3 error

DTC - 56 Quad Driver Module (QDM B) error

DTC - 57 Boost Control error

DTC - 58 Trans fluid temp sensor circuit error (low voltage)

DTC - 58 VATS system error

DTC - 59 Trans fluid temp sensor circuit error (high voltage)

DTC - 61 A/C system performance

DTC - 63 Right bank O2 sensor circuit error

DTC - 63 MAP sensor circuit signal voltage high (low vacuum indicated)

DTC - 64 Right bank O2 sensor lean exhaust indicated

DTC - 64 MAP sensor circuit signal voltage low (high vacuum indicated)

DTC - 65 Right bank O2 sensor rich exhaust indicated

DTC - 66 A/C pressure sensor circuit error (low pressure indicated)

DTC - 67 A/C pressure sensor circuit error

DTC - 68 A/C clutch relay circuit error (shorted to ground)

DTC - 69 A/C clutch relay circuit error (open circuit indicated)

DTC - 69 A/C high pressure switch error

DTC - 70 A/C pressure sensor circuit error (high pressure indicated)

DTC - 71 A/C evaporator temp sensor circuit error (low temp indicated)

DTC - 72 VSS signal circuit error

DTC - 73 A/C evaporator temp sensor circuit error (high temp indicated)

DTC - 75 Digital EGR solenoid #1 circuit error

DTC - 76 Digital EGR solenoid #2 circuit error

DTC - 77 Digital EGR solenoid #3 circuit error

DTC - 79 Transmission fluid overtemp

DTC - 80 Transmission component slipping

DTC - 82 3x Crankshaft position sensor circuit error

DTC - 85 PROM error

DTC - 86 A/D error

DTC - 87 EEPROM error (flash memory error)

DTC - 90 TCC error

DTC - 93 Transmission pressure control solenoid circuit error

DTC - 96 Transmission system voltage low

DTC - 98 Invalid PCM program

DTC - 99 Invalid PCM program