SPN 94 FMI 1FuelHigh
Engine Fuel Delivery Pressure — Low
Scan Tool — in guided session
DVOM Testing — in guided session
Connector Pinout — in guided session
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Overview
Fault Code
SPN 94 / FMI 1
Category
Fuel
Fault Type
sensor
FMI Category
performance
Severity
High
Derate Risk
Yes
Regen Inhibit
No
Inducement Risk
No
Component Location: Fuel delivery pressure sensor — on fuel supply line; fuel filter — on engine or frame rail
Common Symptoms
- Fuel delivery pressure low
- Hard start
- Engine stall
- Low power
- Black smoke
Root Causes
- Fuel filter restriction
- Fuel supply pump failed
- Fuel line restriction
- Fuel tank pickup tube blocked
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Derate Behavior
Power Derate
Yes
Mileage / Regen Notes
Fuel filter restriction common at 15k–25k miles. Fuel pump failure at 300k–500k miles.
System Interactions
SPN 94 FMI 1 interacts with the following systems and may trigger cascading faults if not resolved promptly.
TSB Reference: Cummins TSB 4021682 — Fuel Delivery Pressure Low Diagnosis
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.
OEM Notes
Cummins
X15: Check fuel filter first. Most common cause.
Detroit
DD15: Check fuel supply pump output pressure.
PACCAR
MX-13: Check fuel tank pickup tube.
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OEM System Resources
ASE Training Resources
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Related Diagnostic Articles
Deep-dive diagnostic page: SPN 94 FMI 1 — 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.
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.EPA Aftertreatment & Emissions GuidelinesU.S. EPA heavy-duty diesel aftertreatment compliance, DPF/SCR regulations, and NOx standards.
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