SPN 4357 FMI 0EGR
EGR Temperature Sensor - Data Valid But Above Normal
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Overview
Fault Code
SPN 4357 / FMI 0
Category
EGR
Derate Risk
Possible
Regen Inhibit
No
Inducement Risk
No
Component Location: EGR temperature sensor is mounted on the EGR cooler outlet or EGR mixer inlet on the engine, typically on the driver side of the engine block near the intake manifold.
Common Symptoms
- Check engine light illuminated
- EGR system derate or power loss
- Excessive EGR cooler outlet temperature readings
- Poor engine performance or rough idle
- Increased NOx emissions
- EGR valve commanding closed or reduced flow
- Elevated intake manifold temperatures
Root Causes
- Actual EGR cooler overcooling failure or bypass valve stuck open causing excessive temperature Faulty EGR temperature sensor reading high due to internal sensor drift or failure EGR cooler degradation or partial blockage causing elevated exhaust gas temperatures High engine load combined with high ambient temperatures exceeding normal EGR temp range EGR valve stuck open allowing excessive hot exhaust gas flow Coolant flow restriction to EGR cooler causing reduced cooling efficiency Wiring or connector issue causing signal voltage to read at high end of range ECM software or calibration issue misinterpreting sensor signal
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Derate Behavior
Power Derate
Possible
Mileage / Regen Notes
An above-normal EGR temperature fault (FMI 0) may inhibit or delay active DPF regeneration as the ECM may reduce EGR flow or derate engine to protect EGR components; some platforms will disable regen until fault is resolved to prevent further thermal stress.
System Interactions
SPN 4357 FMI 0 interacts with the following systems and may trigger cascading faults if not resolved promptly.
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.
Related Faults in This Category
OEM System Resources
ASE Training Resources
Diagnostic Engine v7.0
Related Diagnostic Articles
Deep-dive diagnostic page: SPN 4357 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.
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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