Hummer >> H2, H3, H3T (2003 – 2009)

Model Year Engine identification System
H26.0/6.2L 2003-09 VIN  position 8 = L/U GM
H33.5/3.7L 2006-09 VIN  position 8 = 6/E GM
H3T 3.7/5.3L 2009 VIN  position 8 =  E/L GM

General information

  • Refer to the front of this manual for general test conditions, terminology, detailed descriptions of wiring faults and a general trouble shooter for electrical and mechanical faults.
  • 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 OBO-II trouble code tables
P1101 Intake airflow -incorrect Wiring, mechanical fault, engine coolant temperature (EeT) sensor, barometric pressure (BARO) sensor, intake air temperature (IAT) sensor, manifold absolute pressure (MAP) sensor, mass air flow (MAF) sensor, throttle position (TP) switch
P1106 Manifold absolute pressure (MAP) sensor voltage high, intermittent Wiring open circuit/short circuit to positive, poor connections
P1107 Manifold absolute pressure (MAP) sensor voltagelow, intermittent Wiring short circuit to ground, poor connections
P1111 Intake air temperature (lAT) sensor -voltage high, intermittent Wiring open circuit/short to positive, poor connections
P1112 Intake air temperature (IAT) sensor -voltage low, intermittent Wiring short circuit to ground
P1114 Engine coolant temperature (ECT) sensor voltage low, intermittent Wiring short circuit to ground, poor connections
P1115 Engine coolant temperature (ECT) sensor voltage high, intermittent Wiring open circuit/short to positive, poor connections
P1125 Accelerator pedal position (APP) sensor 1/2 signal malfunction Wiring, APP sensor, ECM
P1133 Heated oxygen sensor (H02S) 1, bank 1 insufficient switching Wiring, exhaust system leaking, H02S
P1134 Heated oxygen sensor (H02S) 1, bank 1 slow response Wiring, oxygen sensor heater, exhaust system leaking, H02S
P1153 Heated oxygen sensor (H02S) 1, bank 2 insufficient switching Wiring, oxygen sensor heater, exhaust system leaking, H02S
P1154 Heated oxygen sensor (H02S) 1, bank 2 slow response Wiring, oxygen sensor heater, exhaust system leaking, H02S
P1174 Heated oxygen sensor (H02S) 1, bank 1 mixture variation between cylinders Intake/exhaust leak/blockage, mechanical fault, ignition control, H02S
P1175 Heated oxygen sensor (H02S) 1, bank 2 mixture variation between cylinders Intake/exhaust leak/blockage, mechanical fault, ignition control, H02S
P1255 Fuel pump control module -driver over- temperature Fuel pump control module
P1380 Antilock brake system (ABS)/traction control system (TCS), rough road signal to ECM -malfunction ABS trouble code(s) stored
P1381 Antilock brake system (ABS)/traction control system (TCS), rough road signal to ECM -no communication Wiring, poor connections, ABS
P1400 Cold start emission control -malfunction Intake/exhaust leak/blockage, mechanical fault, idle speed control (ISC) system, ignition control, engine coolant temperature (ECT) sensor, H02S
P1514 Throttle control unit, intake air flow -excessive Throttle control unit, MAP sensor, CMP sensor signal, ECM
P1515 Throttle command/actual throttle pOSition – signal variation Wiring, throttle valve sticking, throttle control module
P1516 Throttle command/actual throttle pOSition – signal variation Wiring, throttle valve sticking, throttle control module
P1518 Throttle control module/engine control module (ECM) -communication malfunction Wiring, throttle control module, ECM
P1600 Engine control module (ECM) -malfunction Engine control module (ECM)
P1621 Engine control module (ECM) memory performance ECM
P1627 Engine control module (ECM) -malfunction Engine control module (ECM)
P1637 Altemator ‘L’ terminal -circuit malfunction Wiring open circuit/short circuit to ground, alternator, battery temperature sensor, ECM
P1638 Altemator ‘F’ terminal -circuit malfunction Wiring open circuit/short circuit to ground, alternator, ECM
P1680 Engine control module (ECM) -malfunction Engine control module (ECM)
P1681 Engine control module (ECM) -malfunction Engine control module (ECM)
P1682 Throttle control module/engine control module (ECM) -ignition power supply variation Wiring, ECM
P1683 Engine control module (ECM) -malfunction Engine control module (ECM)
P1810 Transmission fluid pressure (TFP) switch -manual valve position Fluid level low, wiring, selector lever linkage incorrectly adjusted, ECMITCM
P1815 Transmission fluid pressure (TFP) switch invalid gear selection Wiring, selector lever linkage incorrectly adjusted, TFP switch, ECM
P1816 Transmission fluid pressure (TFP) switch -invalidgear selection Wiring, selector lever linkage incorrectly adjusted,TFP switch, ECMITCM
P1860 Torque converter clutch (TCC) solenoid, pulse width modulation (PWM) -circuit malfunction Wiring open circuit/short circuit to ground, TCCsolenoid, ECM
P1875 Transmission, 4WD low selection signal -circuit malfunction Wiring, transmission, four wheel drive control module, ECM