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

Model Year Engine identification System
G-Series 6.5L Diesel 1996 YIN  position 8 =  Y GM
Sayana 6.5L Diesel 1996-02 YIN  position 8 =  F,  S GM
Savana 6.6L Turbo Diesel 2006-09 YIN  position 8 =  2IW GM
Sierra C/K Pickup 6.5L Turbo Diesel 1996-00 YIN  position 8 =  F,  S GM
Sierra C/K Pickup 6.6L Turbo Diesel 2001-09 YIN  position 8 =  1/2 GM
Suburban 6.5L Diesel 1996-99 YIN  position 8 =  F GM
Yukon/Denali 6.5L Turbo Diesel 1996-99 YIN  position 8 =  S GM

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 code Fault location Probable cause
PO, P2,UO Refer to OBD-II trouble code tables
P1093 Fuel rail pressure (FRP) sensor, command/actual fuel pressure -signal variation Wiring, poor connections, FRP sensor
P1094 Fuel rail pressure (FRP) sensor -signal out ofrange Wiring, poor connections, FRP sensor
P1125 Accelerator pedal position (APP) sensor 1/2/3 -signal variation Wiring, APP sensor, ECM
P1172 Fuel level sensors. primary & secondary sensorno fuel level change during fuel transfer from secondary to primary tank Wiring. secondary fuel pump, fuel level sensors
P1191 Intake manifold system -air leak Intake hose pipe connections, EGR system, ECM
P1214 Fuel injection pump timing -out of range Fuel injection pump timing incorrectly set, CKP sensor, ECM
P1216 Fuel injection duration -pulse width signal shorter than expected Wiring, fuel injection duration control solenoid, fuel injection pump control module, ECM
P1217 Fuel injection duration -pulse width signal longerthan expected Wiring, fuel injection duration control solenoid, fuel injection pump control module, ECM
P1218 Fuel injection pump calibration resistor-circuit malfunction Wiring, calibration resistor
P1223 Injector 1 -circuit malfunction Wiring, injector, FICM
P1224 Injector 1 -circuit malfunction Wiring, injector, ECM
P1226 Injector 2 -circuit malfunction Wiring, injector, FICM
P1227 Injector 2 -circuit malfunction Wiring, injector, ECM
P1229 Injector 3 -circuit malfunction Wiring, injector, FICM
P122A Injector 3 -circuit malfunction Wiring, injector, ECM
P1232 Injector 4 -circuit malfunction Wiring, injector, FICM
P1233 Injector 4 -circuit malfunction Wiring, injector, ECM
P1235 Injector 5 -circuit malfunction Wiring, injector, FICM
P1236 Injector 5 -circuit malfunction Wiring, injector, ECM
P1238 Injector 6 -circuit malfunction Wiring, injector, FICM
P1239 Injector 6 -circuit malfunction Wiring, injector, ECM
P1241 Injector 7 -circuit malfunction Wiring, injector, FICM
P1242 Injector 7 -circuit malfunction Wiring, injector, ECM
P1244 Injector 8 -circuit malfunction Wiring, injector, FICM
P1247 Injector 8 -circuit malfunction Wiring, injector, ECM
P1261 Injectors 1, 4, 6 & 7 -high voltage Wiring, injector(s), ECM
P1262 Injectors 2, 3, 5 & 8 -high voltage Wiring, injector(s), ECM
P1270 Engine control module (ECM). APP sensor signal -analogue/digital process malfunction Engine control module (ECM)
P1271 Accelerator pedal position (APP) sensor 1/2signal variation Wiring, APP sensor, ECM
P1272 Accelerator pedal position (APP) sensor 2/3signal variation Wiring, APP sensor, ECM
P1273 Accelerator pedal position (APP) sensor 1/3signal variation Wiring, APP sensor, ECM
P1277 Accelerator pedal position (APP) sensor 1voltage low Wiring, APP sensor, ECM
P1278 Accelerator pedal position (APP) sensor 1 voltage high Wiring, APP sensor, ECM
P1282 Accelerator pedal position (APP) sensor 2 voltage low Wiring, APP sensor, ECM
P1283 Accelerator pedal position (APP) sensor 2 voltage high Wiring, APP sensor, ECM
P1287 Accelerator pedal position (APP) sensor 3 voltage low Wiring, APP sensor, ECM
P1288 Accelerator pedal position (APP) sensor 3 voltage high Wiring, APP sensor, ECM
P1293 Injector control module -circuit malfunction bank 1 Injector control module
P1294 Injector control module -circuit malfunction bank 2 Injector control module
P1295 Injector control module -circuit malfunction bank 1 Injector control module
P1296 Injector control module -circuit malfunction bank 2 Injector control module
P1345 Crankshaft position (CKP) sensor/camshaft position (CMP) sensor -signal variation Wiring, CKP sensor, CMP sensor
P1404 Exhaust gas recirculation (EGR) vacuum sensor/barometric pressure (BARO) sensorvoltage low Wiring, EGR vacuum sensor/BARO sensor, ECM
P1406 Exhaust gas recirculation (EGR) valve position sensor range performance Wiring, EGR valve tight/sticking, EGR valve position sensor
P1409 Exhaust gas recirculation (EGR) systemmalfunction Wiring, vacuum pipes, EGR vacuum sensor, EGR valve
P1431 Fuel level sensor, secondary -circuit malfunction Wiring, fuel level sensor
P1432 Fuel level sensor -low voltage Wiring open circuit, fuel level sensor
P1433 Fuel level sensor -high voltage Wiring short circuit to positive, fuel level sensor
P1550 System voltage low Wiring, battery, alternator
P154A Intake air heater -feedback circuit Wiring, glow plug control module, intake air heater
P154B Intake air heater -voltage signal circuit Wiring, glow plug control module, intake air heater
P154C Intake air heater -current signal circuit Wiring, glow plug control module, intake air heater
P154D Intake air heater -temperature signal circuit Wiring, glow plug control module, intake air heater
P1600 Engine control module (ECM) -malfunction ECM
P1621 Engine control module (ECM) -memoryperformance ECM
P1626 Engine control module (ECM) -fuel enable signallost Wiring, poor connections, immobilizer control module, ECM
P1627 Engine control module (ECM) -analogue/ digital performance Engine control module (ECM)
P1630 Engine control module (ECM), immobilizer code -learning mode ECM immobilizer code programming not completed
P1631 Engine control module (ECM) -incorrect immobilizer code Incorrect key, immobilizer code not programmed
P1635 Engine control module (ECM), sensor supply voltage -circuit malfunction Wiring short to ground, poor connections, CKP sensor, EGR control/BARO sensor, injectionpump position/fuel temperature sensor, TC boost pressure sensor, ECM
P1637 Altemator waming lamp, control signal -circuit malfunction Wiring, instrument panel, ECM
P1639 Engine control module (ECM), sensor supplyvoltage -circuit malfunction Wiring, poor connections, APP sensor, TC boost pressure sensor, BARO sensor, ECM
P1641 Malfunction indicator lamp (MIL) -circuitmalfunction Wiring, fuses, MIL
P1643 Glow plug waming lamp -circuit malfunction Wiring, glow plug warning lamp, ECM
P1653 Exhaust gas recirculation (EGR) vent valve circuit malfunction Wiring, poor connections, EGR vent valve, ECM
P1654 Service throttle soon warning lamp -circuit malfunction Wiring, fuses, service throttle soon warning lamp
P1655 Exhaust gas recirculation (EGR) control valve -circuit malfunction Wiring, poor connections, EGR control valve,ECM
P1656 Turbocharger (TC) wastegate regulating valve -circuit malfunction Wiring, TC wastegate regulating valve, ECM
P1658 Fuel injector control module (FICM) malfunction FICM
P1680 Engine control module (ECM) -malfunction ECM
P1681 Engine control module (ECM) -malfunction ECM
P1683 Engine control module (ECM) -malfunction ECM
P1687 Fuel injector control module (FICM) -stuck on ECM, FICM
P1781 Transmission control module (TCM), malfunction indicator lamp (MIL) request signal -volta~ehighllow Wiring TCM, ECM
P1810 Transmission gear pressure switch, signal -circuitmalfunction Wiring open circuit/short circuit to ground,reverse/D1/D2/D3/D4 gear pressure switch(es), ECM
P1811 Shift time too long -adaptation limit reached Fluid level low, transmission mechanical fault
P1860 Torque converter clutch (TCC) solenoid, pulse width modulation (PWM) -circuit malfunction Wiring open circuit/short circuit to ground, TCC solenoid, ECM
P1870 Torque converter clutch (TCC) -slip speed excessive Transmission fluid level, wiring, TCC solenoid, ECM
U1026 Transmission control module (TCM)/four wheel drive control module, CAN data bus -communication malfunction Wiring, SCM
U1192 Engine control module (ECM)limmobilizer control module, CAN data bus -signal malfunction Wiring, immobilizer control module, ECM
U1800 Engine control module (ECM)/fuel injector control module (FICM), CAN data bus -communication malfunction Wiring, FICM, ECM
U2104 Engine control module (ECM)/transmission control module (TCM)/Fuel injector control module (FICM), CAN data bus communication malfunction Wiring, TCM, FICM, ECM