SPN 2455 FMI 0Aftertreatment
DPF Pressure Sensor Circuit High
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Overview
Fault Code
SPN 2455 / FMI 0
Category
Aftertreatment
Derate Risk
No
Regen Inhibit
No
Inducement Risk
No
Component Location: DPF differential pressure sensor is typically mounted on the DPF canister or nearby chassis rail, connected via two small hoses to the DPF inlet and outlet pressure ports.
Common Symptoms
- DPF differential pressure reading above normal operating range
- Check engine light or MIL illuminated
- High exhaust backpressure indicated
- Frequent or continuous regen requests
- Poor engine performance or lack of power
- Black smoke from exhaust stack
- Forced parked regen required message
Root Causes
- Plugged or restricted DPF differential pressure sensor signal hoses/tubes (soot or moisture blockage)
- DPF differential pressure sensor failed high (internal sensor fault)
- Short to voltage in the sensor signal wire
- Damaged or corroded sensor connector causing high signal voltage
- Kinked, cracked, or disconnected pressure sensing hoses between sensor and DPF ports
- DPF heavily loaded or completely plugged causing extreme pressure differential
- Failed ECM analog input circuit (rare)
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Derate Behavior
Power Derate
No
Mileage / Regen Notes
SPN 2455 FMI 0 (circuit high / pressure above normal) will typically inhibit active DPF regeneration as the ECM cannot confirm a valid differential pressure reading. The system may default to a DPF over-loaded condition and illuminate the high-exhaust temperature or DPF warning lamp. Parked and forced regens may be blocked until the fault is resolved.
System Interactions
SPN 2455 FMI 0 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
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.
Related Faults in This Category
OEM System Resources
ASE Training Resources
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Related Diagnostic Articles
Deep-dive diagnostic page: SPN 2455 FMI 0 — 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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