SPN 3719 FMI 16AftertreatmentHigh
Aftertreatment 1 DPF Soot Load Percent - Data Valid But Above Normal (Moderately Severe)
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Overview
Fault Code
SPN 3719 / FMI 16
Category
Aftertreatment
Fault Type
system
FMI Category
above normal
Severity
High
Derate Risk
Yes
Regen Inhibit
No
Inducement Risk
No
Component Location: DPF soot load is a calculated parameter - no single sensor. Based on DPF differential pressure sensor readings and exhaust flow model. DPF differential pressure sensor is mounted on the aftertreatment assembly or frame rail with hoses to DPF inlet and outlet pressure taps.
Common Symptoms
- DPF soot load percent above normal threshold - typically 80–100%
- Active regeneration commanded frequently or continuously
- Engine derate may be active if soot load reaches critical level
- Regen not completing - soot load not decreasing after regen attempt
- Possible companion faults: SPN 3251 (DPF differential pressure high), SPN 3031 (DPF inlet temp high)
- Regen inhibit lamp may be illuminated if operator has inhibit switch active
Root Causes
- Regen inhibit switch active - operator preventing regen, allowing soot to accumulate
- Short-trip operation - engine not reaching temperature for passive regen
- Regen not completing - active regen interrupted before soot is fully burned
- DPF differential pressure sensor fault - false high soot load reading
- Engine oil consumption - oil burning in exhaust accelerates soot accumulation
- Fuel injector issue - incomplete combustion increasing soot production
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Derate Behavior
Power Derate
Yes
Mileage / Regen Notes
DPF soot accumulation increases with short-trip operation and high idle time. Ash accumulation (requiring DPF cleaning) increases with mileage regardless of operation.
System Interactions
SPN 3719 FMI 16 interacts with the following systems and may trigger cascading faults if not resolved promptly.
DPF differential pressure monitoring — soot load calculations affected
SCR NOx conversion efficiency — DEF dosing strategy may be altered
Active regen inhibit logic — regen may be blocked or delayed
Engine protection derate — ECM may reduce power to protect components
TSB Reference: Cummins TSB 4021834 - DPF Soot Load Diagnosis and Regen Procedure; Detroit TSB 18-005 - DPF Soot Load Above Normal
Common Diagnostic Mistakes
Replacing the sensor without verifying wiring continuity and supply voltage first.
Clearing codes without identifying and resolving the root cause — the fault will return.
Ignoring related active faults — cascading faults often share a root cause.
Skipping the connector inspection — corrosion and damaged pins are a leading cause of sensor faults.
Condemning the ECM before exhausting all wiring and component tests.
Replacing the DPF without verifying the regen system is functional — a failed regen injector will reload the new DPF.
Ignoring DEF quality — contaminated DEF causes SCR efficiency faults that look like hardware failures.
OEM Notes
Cummins
X15: Regen inhibit switch misuse is the most common cause of high soot load. INSITE DPF regen test required. Cummins recommends stationary regen if soot load is above 80%.
Detroit
DD15: Short-trip operation is a major contributor to high soot load on DD15. DDDL DPF analysis required. Detroit recommends highway driving after regen to confirm soot load reduction.
PACCAR
MX-13: DPF differential pressure sensor hose blockage is common on MX-13 - causes false high soot load. Inspect hoses before performing regen.
Volvo
MP8: Oil consumption from worn valve seals is a common cause of accelerated DPF loading on MP8. PTT DPF test required.
Related Faults in This Category
OEM System Resources
ASE Training Resources
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Related Diagnostic Articles
Deep-dive diagnostic page: SPN 3719 FMI 16 — Full FSM Sequence & Repair Steps — includes wiring notes, sensor specs, and gated repair procedures.
Authority References
Diagnostic procedures on this page are informed by OEM service literature and industry standards.
EPA Aftertreatment & Emissions GuidelinesU.S. EPA heavy-duty diesel aftertreatment compliance, DPF/SCR regulations, and NOx standards.Cummins QuickServe OnlineOfficial Cummins service manuals, fault code lookup, and TSB database.Detroit Diesel DiagnoCentralDetroit Diesel diagnostic procedures, DDDL documentation, and service literature.PACCAR MX Engine ServicePACCAR MX-11 and MX-13 engine service documentation and DAVIE diagnostic guides.Volvo/Mack Tech ToolVolvo and Mack engine fault code reference and PTT/Tech Tool diagnostic procedures.ASE — Diesel Truck Technician CertificationNational Institute for Automotive Service Excellence — T2 Diesel Engines certification standards.
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