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Cummins ISX15 Fault Codes
Complete diagnostic trouble code reference for the Cummins ISX15 heavy-duty diesel engine. 39 fault codes • Protocols: J1587, J1939
🔧 Engine Context: The Cummins ISX15/X15 series is the most common heavy-duty diesel engine in North America, powering Freightliner Cascadia, Kenworth T680, and Peterbilt 579 trucks. Introduced in 2007, the ISX15 has gone through multiple emissions control iterations — from EGR-only to SCR+DEF. Each iteration introduced new fault codes. The most common issues on this series include VGT turbo actuator failures, EGR system problems, and engine protection derate events.
SPN 1569 FMI 31
Engine Protection Torque Derate
Component: Engine Control Module (ECM) • J1939
SPN:1569 FMI:31
SPN 102 FMI 18
Intake Manifold Pressure critically low
Component: Turbocharger / Charge Air System • J1939
SPN:102 FMI:18
SPN 111 FMI 18
Engine Coolant Level critically low
Component: Coolant Level Sensor / Cooling System • J1939
SPN:111 FMI:18
SPN 639 FMI 9
J1939 CAN Bus Communication Loss
Component: Engine Control Module / CAN Bus • J1939
SPN:639 FMI:9
SPN 1322 FMI 31
Misfire Detected on Cylinder 6
Component: Cylinder 6 Injector / Valve Train • J1939
SPN:1322 FMI:31
MID 128 SID 1 FMI 5
Injector Cylinder 1 Circuit
Component: Fuel Injector #1 Solenoid Circuit • J1587
MID:128 PID:
SPN 191 FMI 16
Transmission Output Shaft Speed
Component: Transmission Output Speed Sensor (TOSS) • J1939
SPN:191 FMI:16
MID 128 PID 102 FMI 3
Boost Pressure Sensor
Component: Intake Manifold Pressure Sensor • J1587
MID:128 PID:102
SPN 94 FMI 1
Fuel Delivery Pressure Low
Component: Fuel Supply System • J1939
SPN:94 FMI:1
SPN 157 FMI 16
Fuel Injection Pump Pressure Low
Component: High Pressure Fuel Pump • J1939
SPN:157 FMI:16
SPN 157 FMI 0
Fuel Injection Pump Pressure High
Component: High Pressure Fuel System • J1939
SPN:157 FMI:0
SPN 102 FMI 4
Boost Pressure Sensor Low Voltage
Component: Turbocharger Boost Pressure Sensor • J1939
SPN:102 FMI:4
SPN 3251 FMI 0
DPF Soot Load Critical
Component: Diesel Particulate Filter (DPF) • J1939
SPN:3251 FMI:0
SPN 3251 FMI 16
DPF Soot Level High
Component: Diesel Particulate Filter (DPF) • J1939
SPN:3251 FMI:16
SPN 3246 FMI 0
SCR NOx Conversion Low
Component: SCR Catalyst System • J1939
SPN:3246 FMI:0
SPN 3226 FMI 4
Outlet NOx Sensor Voltage Low
Component: Aftertreatment Outlet NOx Sensor • J1939
SPN:3226 FMI:4
SPN 4076 FMI 4
DEF Doser Circuit Low Voltage
Component: DEF Dosing Unit • J1939
SPN:4076 FMI:4
SPN 3364 FMI 2
DEF Injector Data Erratic
Component: DEF Injector • J1939
SPN:3364 FMI:2
SPN 4364 FMI 18
SCR Inducement Derate Active
Component: SCR Aftertreatment System • J1939
SPN:4364 FMI:18
SPN 1761 FMI 31
DEF Quality Below Specification
Component: DEF Fluid System • J1939
SPN:1761 FMI:31
SPN 3031 FMI 16
DEF Tank Level Low
Component: DEF Tank Level Sensor • J1939
SPN:3031 FMI:16
SPN 5484 FMI 0
DPF Auto Regen Failed
Component: DPF Regeneration System • J1939
SPN:5484 FMI:0
SPN 5246 FMI 0
SCR Severe Derate Active
Component: SCR Aftertreatment System • J1939
SPN:5246 FMI:0
SPN 4331 FMI 16
Outlet NOx Above Threshold
Component: SCR System / NOx Sensor • J1939
SPN:4331 FMI:16
SPN 4752 FMI 0
EGR Valve Position High
Component: EGR Valve • J1939
SPN:4752 FMI:0
SPN 3480 FMI 4
NOx Sensor Heater Voltage Low
Component: Outlet NOx Sensor Heater • J1939
SPN:3480 FMI:4
SPN 108 FMI 3
Baro Pressure Sensor Voltage High
Component: Barometric Pressure Sensor • J1939
SPN:108 FMI:3
SPN 625 FMI 2
J1939 Multiplexing Error
Component: J1939 Data Link / Multiplexed Message Source • J1939
SPN:625 FMI:2
SPN 1761 FMI 19
AFT Outlet NOx Signal Erratic
Component: Aftertreatment Outlet NOx Sensor / Sensor Wiring • J1939
SPN:1761 FMI:19
SPN 3556 FMI 0
DPF Intake Temperature High
Component: DPF Intake Temperature Sensor / Aftertreatment System • J1939
SPN:3556 FMI:0
SPN 100 FMI 1
Engine Oil Pressure Low
Component: Engine Lubrication System / Oil Pump • J1939
SPN:100 FMI:1
SPN 110 FMI 0
Engine Coolant Temperature High
Component: Engine Cooling System / Water Pump / Fan Clutch • J1939
SPN:110 FMI:0
SPN 105 FMI 3
Intake Manifold Temp Sensor Voltage High
Component: Intake Manifold Temperature Sensor / Wiring Harness • J1939
SPN:105 FMI:3
SPN 111 FMI 1
Engine Coolant Level Low
Component: Cooling System / Coolant Level Sensor • J1939
SPN:111 FMI:1
SPN 1569 FMI 0
Engine Torque Derate Active
Component: Engine Control Module (ECM) Protection Strategy • J1939
SPN:1569 FMI:0
SPN 3361 FMI 7
DPF Differential Pressure Mechanical Error
Component: DPF Differential Pressure Sensor / DPF Substrate • J1939
SPN:3361 FMI:7
SPN 4251 FMI 0
DPF Outlet Temperature High
Component: Aftertreatment DPF / Outlet Temperature Sensor • J1939
SPN:4251 FMI:0
SPN 5444 FMI 0
Fuel Filter Differential Pressure High
Component: Fuel System / Primary Fuel Filter • J1939
SPN:5444 FMI:0
SPN 5454 FMI 7
Crankcase Breather Oil Separator Fault
Component: Crankcase Ventilation / Oil Separator • J1939
SPN:5454 FMI:7
Engine Series Coverage:
Cummins ISX15 engine specifications and fault codes sourced from SAE J1939/J1587 public standards and OEM technical service documentation. Last reviewed 2026-08-04T02:30:39Z.