| Scan code | Fault location | Probable cause |
| PO, P2,UO | Refer to OBO-II trouble code tables | – |
| P1110 | Decreased engine performance -high intake air temperature | Wiring open circuit/short to positive, ground wiredefective, IAT sensor, ECT sensor, cooling system, high engine bay temperature, intake manifold heater relay(s), intake manifold heater(s), ECM 1 |
| P1180 | Decreased engine performance -high injection pump fuel temperature | Wiring open circuit/short to positive, ground wire defective, fuel temperature sensor, fueltemperature sensor, mechanical fault, high engine bay temperature, ECM 1 |
| P1192 | Intake air temperature (IAT) sensor -voltage low | Wiring, IAT sensor, ECM 1 |
| P1193 | Intake air temperature (IAT) sensor -voltage high | Wiring, IAT sensor, ECM 1 |
| P1281 | Engine temperature -low for long period | Wiring, cooling system, coolant thermostat, ECT sensor |
| P1283 | Engine control module (ECM) 1 -idle signal malfunction | Wiring, injection pump control module g, ECM 1 |
| P1284 | Injection pump control module -battery voltage out of range | Wiring, injection pump control module, ECM 1 |
| P1285 | Injection pump control module relay -circuitmalfunction | Wiring, injection pump control module relay |
| P1286 | Accelerator pedal position (APP) sensor -highinput | Wiring short to positive, APP sensor, ECM 1 |
| P1287 | Injection pump control module/engine control module (ECM) 1 -supply voltage low | Wiring, battery, alternator |
| P1291 | Intake manifold heaters -no temperature rise | Wiring, intake manifold heater relay(s), intakemanifold heater(s), ECM 1 |
| P1295 | Accelerator pedal position (APP) sensor -low input | Signal wire short circuit to ground, supply wire open circuit, APP sensor, ECM 1 |
| P1296 | Manifold absolute pressure (MAP) sensor no 5 volt supply | Wiring, MAP sensor, ECM 1 |
| P1297 | Manifold absolute pressure (MAP) sensor | Wiring, hose connection(s), MAP sensor |
| P1388 | Engine control relay | Wiring open circuit/short circuit, engine control relay, ECM 2 |
| P1389 | Engine control relay | Wiring open circuit, engine control relay, ECM 2 |
| P1399 | Glow plug waming lamp -circuit malfun~tion | Wiring, glow plug warning lamp, ECM 1 |
| P1475 | Engine control module (ECM) 1 -auxiliary 5 volt output high | Wiring, ECM 1 |
| P1478 | AmbienUbattery temperature sensor -range/ performance problem | Wiring, ambient/battery temperature sensor |
| P1488 | Engine control module (ECM) 1 -auxiliary 5 volt output low | Wiring, ECM 1 |
| P1492 | AmbienUbattery temperature sensor -voltage high | Wiring, ambient/battery temperature sensor |
| P1493 | AmbienUbattery temperature sensor -voltage low | Wiring, ambient/battery temperature sensor |
| P1496 | Engine control module (ECM) 1 -5 volt output low | ECM 1 |
| P1594 | Alternator -voltage high j | Wiring, battery, alternator |
| P1595 | Cruise control | Wiring open circuit/short circuit, hoses, cruise control master switch, cruise control vacuum switching valve, ECM 2 |
| P1596 | Cruise control master switch -high voltage | Wiring, cruise control master switch, ECM 2 |
| P1597 | Cruise control master switch -low voltage | Wiring, cruise control master switch, ECM 2 |
| P1602 | Engine control module (ECM) 1 not programmed | New ECM not programmed, incorrectly programmed, ECM 1 |
| P1682 | Altemator -voltage low | Wiring, battery, alternator drive belt, alternator |
| P1683 | Cruise control | Wiring, cruise control vacuum switching valve, ECM 2 |
| P1684 | Engine control module (ECM) 1 -supply voltage disconnected within last 50 ignition switch ON-OFF cycles | Wiring, battery |
| P1688 | Injection pump/injection pump control module -intemal fault | Injection pump/injection pump control module |
| P1689 | Injection pump control module communication to engine control module (ECM) 1 malfunction | Wiring, poor connection, injection pump control module, ECM 1 |
| P1690 | Crankshaft position/injection pump camshaft position sensor -correlation | Wiring, CKP sensor, injection pump CMP sensor, mechanical fault, ECM 1 |
| P1691 | Injection pump -intemal fault | Injection pump/injection pump control module D |
| P1693 | Engine control module (ECM) 1 | Companion module trouble code detected in ECM 1 |
| P1694 | CAN data bus, engine control module (ECM) 1no signal | Wiring, ECM 1 |
| P1696 | Engine control module (ECM) 1 -EEPROM error | ECM 1 |
| P1698 | CAN data bus, engine control module (ECM) 2no signal | Wiring, ECM 2 |
| P1719 | Skip shift solenoid -circuit malfunction | Wiring open circuit/short circuit, skip shift solenoid |
| P1740 | Torque converter clutch (TCC)/overdrive solenoid-performance problem | TCC, overdrive solenoid, transmission mechanical fault |
| P1756 | Govemor pressure not equal to target (15-20PSI) -mid pressure malfunction | Signal wire open circuit/short circuit, valve body, sensor supply wire open circuit, transmission fluid level, governor pressure solenoid, transmission mechanical fault, ECM 2 no 5 volt supply f) |
| P1757 | Govemor pressure not equal to target (15-20 PSI) -zero pressure malfunction | Signal wire open circuit/short circuit, valve body, sensor supply wire open circuit, transmission fluid level, governor pressure solenoid, transmission mechanical fault, ECM 2 -no 5 volt supply f) |
| P1762 | Govemor pressure sensor -incorrect signal | Signal wire short circuit to ground/ positive, supply wire open circuit/short circuit, transmission fluid level, governor pressure solenoid, governor pressure sensor, ECM 2 f) |
| P1763 | Governor pressure sensor -signal high | Signal wire short circuit to positive, supply wire open circuit, transmission fluid level, governor pressure sensor, ECM 2 6 |
| P1764 | Governor pressure sensor -signal low | Signal wire short circuit to ground, supply wire open circuit, transmission fluid level, governor pressure sensor, ECM 2 6 |
| P1765 | Transmission system relay | Wiring open circuit/short circuit, transmission system relay, ECM 2 |
| P1899 | Park/neutral position (PNP) switch -input circuit malfunction | Wiring, PNP switch, ECM 2 |
