The Cummins ISX engine, first introduced in the late 1990s, quickly became a workhorse in the heavy-duty trucking world. Between 1998 and 2000, the ISX offered fleets improved fuel economy, power output, and more advanced electronics for the era.
Like all modern diesel engines, the ISX relies on fault codes to help techs pinpoint issues faster — keeping trucks on the road and minimizing downtime.
Cummins ISX (1998–2000) Engine Overview
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Displacement: 15.0L
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Horsepower Range: 400–600 HP
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Torque: Up to 2,050 lb-ft
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Emissions System: EGR (Early models)
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Fuel System: High-pressure common rail
Applications: Freightliner, Peterbilt, Kenworth, International, and other Class 8 models.
📍 Get FREE Fault Code Information for all makes and models in Diesel Repair → Diesel Repair
Fault Codes for Cummins ISX (1998–2000)
| Fault | PID | SPN | FMI | SID | Title |
| PID 191 FMI 16 (349) | 191 | 16 | Auxiliary Speed Governor | ||
| SPN 100 FMI 1 (415) | 100 | 100 | 1 | Engine Oil Pressure Low – Critical | |
| SPN 100 FMI 18 (143) | 100 | 100 | 18 | Engine Oil Pressure Low – Warning | |
| SPN 100 FMI 2 (435) | 100 | 100 | 2 | Oil Pressure Sensor | |
| SPN 100 FMI 3 (135) | 100 | 100 | 3 | Oil Pressure Sensor Circuit | |
| SPN 100 FMI 4 (141) | 100 | 100 | 4 | Oil Pressure Sensor Circuit | |
| SPN 102 FMI 2 (433) | 102 | 102 | 2 | Intake Manifold Pressure Circuit | |
| SPN 102 FMI 3 (122) | 102 | 102 | 3 | Intake Manifold Pressure Sensor Circuit | |
| SPN 102 FMI 4 (123) | 102 | 102 | 4 | Intake Manifold Pressure Sensor Circuit | |
| SPN 103 FMI 16 (595) | 103 | 103 | 16 | Turbocharger Speed High (Calculated) | |
| SPN 1043 FMI 11 (496) | 1043 | 11 | 221 | Sensor Supply Voltage | |
| SPN 1043 FMI 3 (387) | 221 | 1043 | 3 | Throttle Voltage Supply | |
| SPN 1043 FMI 4 (284) | 221 | 1043 | 4 | Sensor Supply Voltage | |
| SPN 1043 FMI 4 (443) | 1043 | 4 | 221 | Throttle Voltage Supply | |
| SPN 105 FMI 0 (155) | 105 | 105 | Intake Manifold 1 Temperature – Data Valid but Above Normal Operational Range – Most Severe Level | ||
| SPN 105 FMI 3 (153) | 105 | 105 | 3 | Intake Manifold Temperature Sensor Circuit | |
| SPN 105 FMI 4 (154) | 105 | 105 | 4 | Intake Manifold Temperature Sensor Circuit | |
| SPN 1072 FMI 11 (388) | 1072 | 11 | 79 | Engine Brake Supply Circuit | |
| SPN 1073 FMI 11 (392) | 1073 | 11 | 29 | Engine Brake Supply Circuit | |
| SPN 1079 FMI 3 (386) | 1079 | 3 | 232 | Sensor Voltage Supply | |
| SPN 1083 FMI 3 (293) | 1083 | 3 | 154 | OEM Temperature Sensor Circuit | |
| SPN 1083 FMI 4 (294) | 1083 | 4 | 154 | OEM Temperature Sensor Circuit | |
| SPN 1084 FMI 3 (297) | 1084 | 3 | 223 | OEM Pressure Sensor Circuit | |
| SPN 1084 FMI 4 (298) | 1084 | 4 | 223 | OEM Pressure Sensor Circuit | |
| SPN 108 FMI 2 (295) | 108 | 108 | 2 | Ambient Air Pressure Sensor | |
| SPN 108 FMI 3 (221) | 108 | 108 | 3 | Ambient Air Pressure Sensor Circuit | |
| SPN 108 FMI 4 (222) | 108 | 108 | 4 | Ambient Air Pressure Sensor Circuit | |
| SPN 110 FMI 3 (144) | 110 | 110 | 3 | Coolant Temperature Sensor Circuit | |
| SPN 110 FMI 4 (145) | 110 | 110 | 4 | Coolant Temperature Sensor Circuit | |
| SPN 1112 FMI 11 (393) | 1112 | 11 | 82 | Engine Brake Supply Circuit | |
| SPN 111 FMI 1 (235) | 111 | 111 | 1 | Engine Coolant Level – Engine Protection | |
| SPN 111 FMI 2 (422) | 111 | 111 | 2 | Coolant Level Sensor Circuit | |
| SPN 1188 FMI 3 (465) | 1188 | 3 | 32 | Wastegate Actuator Number 1 Circuit | |
| SPN 1188 FMI 4 (466) | 1188 | 4 | 32 | Wastegate Actuator Number 1 Circuit | |
| SPN 1189 FMI 3 (491) | 1189 | 3 | 88 | Wastegate Actuator Number 2 Circuit | |
| SPN 1189 FMI 4 (492) | 1189 | 4 | 88 | Wastegate Actuator Number 2 Circuit | |
| SPN 1244 FMI 5 (396) | 1244 | 5 | 83 | Actuator Circuit | |
| SPN 1244 FMI 6 (397) | 1244 | 6 | 83 | Actuator Circuit | |
| SPN 1245 FMI 5 (398) | 1245 | 5 | 84 | Actuator Circuit | |
| SPN 1245 FMI 6 (399) | 1245 | 6 | 84 | Actuator Circuit | |
| SPN 1265 FMI 4 (223) | 1265 | 4 | 85 | Burn Valve Solenoid | |
| SPN 1267 FMI 3 (338) | 1267 | 3 | 87 | Idle Shutdown Vehicle Accessory / Ignition Bus Relay Circuit | |
| SPN 1267 FMI 4 (339) | 1267 | 4 | 87 | Idle Shutdown Vehicle Accessory / Ignition Bus Relay Circuit | |
| SPN 1319 FMI 2 (419) | 102 | 1319 | 2 | Intake Manifold Pressure Sensor | |
| SPN 1321 FMI 2 (474) | 1321 | 2 | 237 | Starter Solenoid Lockout Relay Driver Circuit | |
| SPN 1349 FMI 16 (485) | 129 | 1349 | 16 | Fuel System Over Fueling | |
| SPN 1349 FMI 18 (486) | 129 | 1349 | 18 | Fuel System Under Fueling | |
| SPN 1349 FMI 3 (483) | 129 | 1349 | 3 | Rear Rail Pressure Sensor Circuit | |
| SPN 1349 FMI 4 (484) | 129 | 1349 | 4 | Rear Rail Pressure Sensor Circuit | |
| SPN 1349 FMI 7 (758) | 129 | 1349 | 7 | Fuel Injector | |
| SPN 1351 FMI 3 (476) | 1351 | 3 | 89 | Electronic Air Compressor Governor Circuit | |
| SPN 1351 FMI 4 (475) | 1351 | 4 | 89 | Electronic Air Compressor Governor Circuit | |
| SPN 1380 FMI 2 (472) | 1380 | 2 | 17 | Crankcase Oil Level Sensor Circuit | |
| SPN 1381 FMI 18 (583) | 15 | 1381 | 18 | Fuel Inlet Restriction Sensor Circuit | |
| SPN 1381 FMI 3 (581) | 15 | 1381 | 3 | Fuel Inlet Restriction Sensor Circuit | |
| SPN 1381 FMI 4 (582) | 15 | 1381 | 4 | Fuel Inlet Restriction Sensor Circuit | |
| SPN 157 FMI 16 (553) | 157 | 157 | 16 | Fuel System Over Fueling | |
| SPN 157 FMI 18 (559) | 157 | 157 | 18 | Fuel System Under Fueling | |
| SPN 157 FMI 3 (451) | 157 | 157 | 3 | Front Rail Pressure Sensor Circuit | |
| SPN 157 FMI 4 (452) | 157 | 157 | 4 | Front Rail Pressure Sensor Circuit | |
| SPN 157 FMI 7 (755) | 157 | 157 | 7 | Fuel Injector | |
| SPN 1590 FMI 2 (784) | 1590 | 2 | Adaptive Cruise Control Circuit | ||
| SPN 166 FMI 2 (951) | 166 | 166 | 2 | Cylinder Power Imbalance | |
| SPN 167 FMI 1 (598) | 167 | 167 | 1 | Voltage Monitor – Very Low Voltage | |
| SPN 167 FMI 16 (596) | 167 | 167 | 16 | Voltage Monitor – High Voltage | |
| SPN 167 FMI 18 (597) | 167 | 167 | 18 | Voltage Monitor – Low Voltage | |
| SPN 168 FMI 16 (442) | 168 | 168 | 16 | Unswitched Battery Supply Circuit | |
| SPN 168 FMI 18 (441) | 168 | 168 | 18 | Unswitched Battery Supply Circuit | |
| SPN 171 FMI 3 (249) | 171 | 171 | 3 | Ambient Air Temperature Sensor Circuit | |
| SPN 171 FMI 4 (256) | 171 | 171 | 4 | Ambient Air Temperature Sensor Circuit | |
| SPN 175 FMI 0 (214) | 175 | 175 | Engine Oil Temperature High – Data Valid but Above Normal Operational Range – Most Severe Level | ||
| SPN 175 FMI 3 (212) | 175 | 175 | 3 | Oil Temperature Sensor Circuit | |
| SPN 175 FMI 4 (213) | 175 | 175 | 4 | Oil Temperature Sensor Circuit | |
| SPN 190 FMI 0 (234) | 190 | 190 | Engine Overspeed | ||
| SPN 190 FMI 10 (121) | 190 | 190 | 10 | Crankshaft Engine Position Sensor Circuit | |
| SPN 190 FMI 2 (115) | 190 | 190 | 2 | Camshaft Engine Position Sensor Circuit | |
| SPN 191 FMI 18 (489) | 191 | 191 | 18 | Auxiliary Speed Input Error | |
| SPN 251 FMI 2 (319) | 251 | 251 | 2 | Real-Time Clock Power Circuit | |
| SPN 46 FMI 2 (218) | 46 | 46 | 2 | Wet Tank Pressure Sensor Circuit | |
| SPN 46 FMI 3 (216) | 46 | 46 | 3 | Wet Tank Pressure Sensor Circuit | |
| SPN 46 FMI 4 (217) | 46 | 46 | 4 | Wet Tank Pressure Sensor Circuit | |
| SPN 558 FMI 13 (432) | 558 | 13 | 230 | Accelerator Pedal Circuit | |
| SPN 558 FMI 2 (431) | 558 | 2 | 230 | Idle Validation Switch Circuit | |
| SPN 558 FMI 4 (551) | 558 | 4 | 230 | Idle Validation Switch Circuit | |
| SPN 558 FMI 4 (551) | 558 | 4 | 230 | Idle Validation Switch Circuit | |
| SPN 558 FMI 4 (551) | 558 | 4 | 230 | Idle Validation Switch Circuit | |
| SPN 611 FMI 3 (588) | 611 | 3 | 121 | Engine Start Alarm Circuit | |
| SPN 611 FMI 4 (589) | 611 | 4 | 121 | Engine Start Alarm Circuit | |
| SPN 611 FMI 7 (544) | 611 | 7 | 151 | Top 2 Transmission Circuit – Mechanical System Failure | |
| SPN 612 FMI 3 (198) | 612 | 3 | 122 | ICON Lamp Circuit | |
| SPN 612 FMI 4 (199) | 612 | 4 | 122 | ICON Lamp Circuit | |
| SPN 613 FMI 31 (359) | 613 | 31 | 124 | ICON Idle Control System | |
| SPN 614 FMI 2 (469) | 614 | 2 | 215 | ICON Cab Thermostat Circuit | |
| SPN 615 FMI 31 (541) | 615 | 31 | 123 | ICON Starter Relay / Interlock Circuit | |
| SPN 620 FMI 3 (227) | 620 | 3 | 232 | Sensor Voltage Supply | |
| SPN 620 FMI 4 (187) | 620 | 4 | 232 | Sensor Voltage Supply | |
| SPN 620 FMI 4 (352) | 620 | 4 | 232 | Sensor Voltage Supply | |
| SPN 627 FMI 2 (434) | 627 | 2 | 251 | Unswitched Battery Supply Circuit | |
| SPN 629 FMI 12 (111) | 629 | 12 | 254 | Engine Control Module Microprocessor | |
| SPN 629 FMI 12 (343) | 629 | 12 | 254 | Electronic Control Module Warning Internal Hardware Failure – Bad Intelligent Device or Component | |
| SPN 630 FMI 2 (341) | 630 | 2 | 253 | Unswitched Battery Supply Circuit | |
| SPN 632 FMI 3 (255) | 632 | 3 | 17 | Engine Fuel Shutoff Valve Drive Circuit – Voltage Above Normal or Shorted to High Source | |
| SPN 632 FMI 4 (254) | 632 | 4 | 17 | Fuel Shutoff Valve Solenoid Supply Circuit | |
| SPN 632 FMI 7 (259) | 632 | 7 | 17 | Fuel Shutoff Valve | |
| SPN 633 FMI 5 (378) | 633 | 5 | 18 | Actuator Circuit | |
| SPN 633 FMI 6 (379) | 633 | 6 | 18 | Actuator Circuit | |
| SPN 635 FMI 5 (394) | 635 | 5 | 20 | Actuator Circuit | |
| SPN 635 FMI 6 (395) | 635 | 6 | 20 | Actuator Circuit | |
| SPN 639 FMI 13 (286) | 639 | 13 | 231 | J1939 Datalink Multiplexing | |
| SPN 639 FMI 2 (426) | 639 | 2 | 231 | J1939 Datalink Communication | |
| SPN 639 FMI 9 (285) | 639 | 9 | 231 | J1939 Datalink Multiplexing | |
| SPN 647 FMI 4 (245) | 647 | 4 | 33 | Engine Fan Clutch Supply Circuit | |
| SPN 702 FMI 3 (527) | 40 | 702 | 3 | 154 | Switched Output A Error |
| SPN 703 FMI 3 (529) | 703 | 3 | 51 | Switched Output B Error | |
| SPN 717 FMI 11 (537) | 717 | 11 | 43 | Autoshift High Gear Actuator (Shift Solenoid) Circuit | |
| SPN 718 FMI 11 (536) | 718 | 11 | 44 | Autoshift Low Gear Actuator (Lockout Solenoid) Circuit | |
| SPN 719 FMI 11 (538) | 719 | 11 | 45 | Auto Shift Neutral Actuator | |
| SPN 723 FMI 2 (753) | 723 | 2 | 64 | Engine Speed Sensor Circuit | |
| SPN 723 FMI 7 (731) | 723 | 7 | 64 | Engine Speed Sensor and Camshaft Position Sensor – Mechanical Misalignment Between Camshaft and Crankshaft Sensors | |
| SPN 84 FMI 10 (242) | 84 | 84 | 10 | Vehicle Speed Sensor Circuit | |
| SPN 84 FMI 2 (241) | 84 | 84 | 2 | Vehicle Speed Sensor Circuit | |
| SPN 91 FMI 2 (431) | 91 | 91 | 2 | Idle Validation Switch Circuit | |
| SPN 91 FMI 2 (431) | 91 | 91 | 2 | Idle Validation Switch Circuit | |
| SPN 91 FMI 3 (131) | 91 | 91 | 3 | Accelerator Position Sensor Circuit | |
| SPN 91 FMI 4 (132) | 91 | 91 | 4 | Accelerator Position Sensor Circuit | |
| SPN 91 FMI 8 (147) | 91 | 91 | 8 | Frequency Throttle Circuit | |
| SPN 91 FMI 8 (148) | 91 | 91 | 8 | Frequency Throttle Circuit | |
| SPN 93 FMI 2 (528) | 93 | 93 | 2 | Switched Output B Error | |
| SPN 94 FMI 16 (449) | 94 | 94 | 16 | High Fuel Pressure | |
| SPN 94 FMI 18 (482) | 94 | 94 | 18 | Fuel Pressure Low – Data Valid but Below Normal Operating Range – Moderately Severe Level | |
| SPN 94 FMI 3 (546) | 94 | 94 | 3 | Fuel Pressure Sensor Circuit | |
| SPN 94 FMI 4 (547) | 94 | 94 | 4 | Fuel Pressure Sensor Circuit | |
| SPN 974 FMI 3 (133) | 29 | 974 | 3 | Remote Throttle Position Sensor Circuit | |
| SPN 974 FMI 4 (134) | 29 | 974 | 4 | Remote Throttle Position Sensor Circuit | |
| SPN 97 FMI 3 (428) | 97 | 97 | 3 | Water-In-Fuel (WIF) Sensor Circuit | |
| SPN 97 FMI 4 (429) | 97 | 97 | 4 | Water-In-Fuel (WIF) Sensor Circuit |
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