GMC OBD/OBD2 Codes >> G-Series – Savana – Sierra – Suburban – Yukon/Denali

ModelYearEngine identificationSystem
G-Series 6.5L Diesel1996YIN  position 8 =  YGM
Sayana 6.5L Diesel1996-02YIN  position 8 =  F,  SGM
Savana 6.6L Turbo Diesel2006-09YIN  position 8 =  2IWGM
Sierra C/K Pickup 6.5L Turbo Diesel1996-00YIN  position 8 =  F,  SGM
Sierra C/K Pickup 6.6L Turbo Diesel2001-09YIN  position 8 =  1/2GM
Suburban 6.5L Diesel1996-99YIN  position 8 =  FGM
Yukon/Denali 6.5L Turbo Diesel1996-99YIN  position 8 =  SGM

General information

  • Malfunction indicator lamp (MIL) will illuminate or flash 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 only be displayed by using a Scan Tool connected to the data link connector (DLC) 1.


• After the faults have been rectified, the manufacturer recommends that trouble codes are erased by using a Scan Tool connected to the data link connector (DLC)

Trouble code  identification

Scan codeFault locationProbable cause
PO, P2,UORefer to OBD-II trouble code tables
P1093Fuel rail pressure (FRP) sensor, command/actual fuel pressure -signal variationWiring, poor connections, FRP sensor
P1094Fuel rail pressure (FRP) sensor -signal out ofrangeWiring, poor connections, FRP sensor
P1125Accelerator pedal position (APP) sensor 1/2/3 -signal variationWiring, APP sensor, ECM
P1172Fuel level sensors. primary & secondary sensorno fuel level change during fuel transfer from secondary to primary tankWiring. secondary fuel pump, fuel level sensors
P1191Intake manifold system -air leakIntake hose pipe connections, EGR system, ECM
P1214Fuel injection pump timing -out of rangeFuel injection pump timing incorrectly set, CKP sensor, ECM
P1216Fuel injection duration -pulse width signal shorter than expectedWiring, fuel injection duration control solenoid, fuel injection pump control module, ECM
P1217Fuel injection duration -pulse width signal longerthan expectedWiring, fuel injection duration control solenoid, fuel injection pump control module, ECM
P1218Fuel injection pump calibration resistor-circuit malfunctionWiring, calibration resistor
P1223Injector 1 -circuit malfunctionWiring, injector, FICM
P1224Injector 1 -circuit malfunctionWiring, injector, ECM
P1226Injector 2 -circuit malfunctionWiring, injector, FICM
P1227Injector 2 -circuit malfunctionWiring, injector, ECM
P1229Injector 3 -circuit malfunctionWiring, injector, FICM
P122AInjector 3 -circuit malfunctionWiring, injector, ECM
P1232Injector 4 -circuit malfunctionWiring, injector, FICM
P1233Injector 4 -circuit malfunctionWiring, injector, ECM
P1235Injector 5 -circuit malfunctionWiring, injector, FICM
P1236Injector 5 -circuit malfunctionWiring, injector, ECM
P1238Injector 6 -circuit malfunctionWiring, injector, FICM
P1239Injector 6 -circuit malfunctionWiring, injector, ECM
P1241Injector 7 -circuit malfunctionWiring, injector, FICM
P1242Injector 7 -circuit malfunctionWiring, injector, ECM
P1244Injector 8 -circuit malfunctionWiring, injector, FICM
P1247Injector 8 -circuit malfunctionWiring, injector, ECM
P1261Injectors 1, 4, 6 & 7 -high voltageWiring, injector(s), ECM
P1262Injectors 2, 3, 5 & 8 -high voltageWiring, injector(s), ECM
P1270Engine control module (ECM). APP sensor signal -analogue/digital process malfunctionEngine control module (ECM)
P1271Accelerator pedal position (APP) sensor 1/2signal variationWiring, APP sensor, ECM
P1272Accelerator pedal position (APP) sensor 2/3signal variationWiring, APP sensor, ECM
P1273Accelerator pedal position (APP) sensor 1/3signal variationWiring, APP sensor, ECM
P1277Accelerator pedal position (APP) sensor 1voltage lowWiring, APP sensor, ECM
P1278Accelerator pedal position (APP) sensor 1 voltage highWiring, APP sensor, ECM
P1282Accelerator pedal position (APP) sensor 2 voltage lowWiring, APP sensor, ECM
P1283Accelerator pedal position (APP) sensor 2 voltage highWiring, APP sensor, ECM
P1287Accelerator pedal position (APP) sensor 3 voltage lowWiring, APP sensor, ECM
P1288Accelerator pedal position (APP) sensor 3 voltage highWiring, APP sensor, ECM
P1293Injector control module -circuit malfunction bank 1Injector control module
P1294Injector control module -circuit malfunction bank 2Injector control module
P1295Injector control module -circuit malfunction bank 1Injector control module
P1296Injector control module -circuit malfunction bank 2Injector control module
P1345Crankshaft position (CKP) sensor/camshaft position (CMP) sensor -signal variationWiring, CKP sensor, CMP sensor
P1404Exhaust gas recirculation (EGR) vacuum sensor/barometric pressure (BARO) sensorvoltage lowWiring, EGR vacuum sensor/BARO sensor, ECM
P1406Exhaust gas recirculation (EGR) valve position sensor range performanceWiring, EGR valve tight/sticking, EGR valve position sensor
P1409Exhaust gas recirculation (EGR) systemmalfunctionWiring, vacuum pipes, EGR vacuum sensor, EGR valve
P1431Fuel level sensor, secondary -circuit malfunctionWiring, fuel level sensor
P1432Fuel level sensor -low voltageWiring open circuit, fuel level sensor
P1433Fuel level sensor -high voltageWiring short circuit to positive, fuel level sensor
P1550System voltage lowWiring, battery, alternator
P154AIntake air heater -feedback circuitWiring, glow plug control module, intake air heater
P154BIntake air heater -voltage signal circuitWiring, glow plug control module, intake air heater
P154CIntake air heater -current signal circuitWiring, glow plug control module, intake air heater
P154DIntake air heater -temperature signal circuitWiring, glow plug control module, intake air heater
P1600Engine control module (ECM) -malfunctionECM
P1621Engine control module (ECM) -memoryperformanceECM
P1626Engine control module (ECM) -fuel enable signallostWiring, poor connections, immobilizer control module, ECM
P1627Engine control module (ECM) -analogue/ digital performanceEngine control module (ECM)
P1630Engine control module (ECM), immobilizer code -learning modeECM immobilizer code programming not completed
P1631Engine control module (ECM) -incorrect immobilizer codeIncorrect key, immobilizer code not programmed
P1635Engine control module (ECM), sensor supply voltage -circuit malfunctionWiring short to ground, poor connections, CKP sensor, EGR control/BARO sensor, injectionpump position/fuel temperature sensor, TC boost pressure sensor, ECM
P1637Altemator waming lamp, control signal -circuit malfunctionWiring, instrument panel, ECM
P1639Engine control module (ECM), sensor supplyvoltage -circuit malfunctionWiring, poor connections, APP sensor, TC boost pressure sensor, BARO sensor, ECM
P1641Malfunction indicator lamp (MIL) -circuitmalfunctionWiring, fuses, MIL
P1643Glow plug waming lamp -circuit malfunctionWiring, glow plug warning lamp, ECM
P1653Exhaust gas recirculation (EGR) vent valve circuit malfunctionWiring, poor connections, EGR vent valve, ECM
P1654Service throttle soon warning lamp -circuit malfunctionWiring, fuses, service throttle soon warning lamp
P1655Exhaust gas recirculation (EGR) control valve -circuit malfunctionWiring, poor connections, EGR control valve,ECM
P1656Turbocharger (TC) wastegate regulating valve -circuit malfunctionWiring, TC wastegate regulating valve, ECM
P1658Fuel injector control module (FICM) malfunctionFICM
P1680Engine control module (ECM) -malfunctionECM
P1681Engine control module (ECM) -malfunctionECM
P1683Engine control module (ECM) -malfunctionECM
P1687Fuel injector control module (FICM) -stuck onECM, FICM
P1781Transmission control module (TCM), malfunction indicator lamp (MIL) request signal -volta~ehighllowWiring TCM, ECM
P1810Transmission gear pressure switch, signal -circuitmalfunctionWiring open circuit/short circuit to ground,reverse/D1/D2/D3/D4 gear pressure switch(es), ECM
P1811Shift time too long -adaptation limit reachedFluid level low, transmission mechanical fault
P1860Torque converter clutch (TCC) solenoid, pulse width modulation (PWM) -circuit malfunctionWiring open circuit/short circuit to ground, TCC solenoid, ECM
P1870Torque converter clutch (TCC) -slip speed excessiveTransmission fluid level, wiring, TCC solenoid, ECM
U1026Transmission control module (TCM)/four wheel drive control module, CAN data bus -communication malfunctionWiring, SCM
U1192Engine control module (ECM)limmobilizer control module, CAN data bus -signal malfunctionWiring, immobilizer control module, ECM
U1800Engine control module (ECM)/fuel injector control module (FICM), CAN data bus -communication malfunctionWiring, FICM, ECM
U2104Engine control module (ECM)/transmission control module (TCM)/Fuel injector control module (FICM), CAN data bus communication malfunctionWiring, TCM, FICM, ECM