SPN 4331 FMI 0EGR
EGR Temperature Sensor - Data Valid But Above Normal
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Overview
Fault Code
SPN 4331 / FMI 0
Category
EGR
Derate Risk
No
Regen Inhibit
No
Inducement Risk
No
Component Location: EGR temperature sensor is mounted on the EGR cooler outlet or EGR mixer/valve assembly on the engine, typically near the intake manifold side.
Common Symptoms
- EGR temperature reading excessively high
- Check engine light illuminated
- Increased NOx emissions
- EGR valve may limit flow or stay closed
- Possible engine derate or power loss
- Elevated exhaust gas temperatures
Root Causes
- Actual high EGR gas temperature due to excessive EGR flow or stuck-open EGR valve Clogged or restricted EGR cooler reducing heat dissipation and elevating outlet temperature Faulty EGR temperature sensor reading high (shifted calibration or internal failure) EGR cooler coolant flow restriction or low coolant level reducing cooling capacity Exhaust backpressure elevated due to DPF loading causing increased EGR temperatures Engine running extended high-load cycles with high exhaust temps feeding EGR circuit Damaged or deteriorated EGR cooler with partial bypass of coolant passages Wiring short to voltage source causing falsely elevated sensor signal
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Derate Behavior
Power Derate
No
Mileage / Regen Notes
SPN 4331 FMI 0 may inhibit active DPF regeneration if EGR temperature exceeds safe threshold, as high EGR temps combined with regen exhaust temps could push component temperatures beyond limits. Some platforms will delay or block regen until EGR temps return to normal operating range.
System Interactions
SPN 4331 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.
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OEM System Resources
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Related Diagnostic Articles
Deep-dive diagnostic page: SPN 4331 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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