SPN 1327 FMI 13Engine Protection
Misfire Cylinder 5 - Out of Calibration
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Overview
Fault Code
SPN 1327 / FMI 13
Category
Engine Protection
Derate Risk
Yes
Regen Inhibit
No
Inducement Risk
No
Component Location: Cylinder 5 injector is located in the cylinder head at the 5th cylinder position; on inline-6 engines this is the second-to-last cylinder from the rear of the engine.
Common Symptoms
- Rough idle or vibration
- Loss of power under load
- Increased fuel consumption
- White or gray smoke from exhaust
- Engine runs rough at low RPM
- Check engine light illuminated
Root Causes
- Injector calibration code (IQA/trim code) not programmed or incorrectly entered into ECM for cylinder 5
- Replaced injector on cylinder 5 without updating injector trim/IQA code in ECM
- Faulty or worn fuel injector on cylinder 5 causing delivery deviation beyond calibration limits
- ECM software not updated to support current injector trim code format
- Corrupted or lost injector calibration data in ECM memory after battery disconnect or ECM replacement
- Incorrect injector installed (wrong flow rating or part number) on cylinder 5
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Derate Behavior
Power Derate
Yes
Mileage / Regen Notes
Active and parked DPF regeneration may be inhibited or restricted when a cylinder misfire or out-of-calibration fault is active, as the ECM will limit post-injection strategies and may enter engine protection derate mode to prevent uncontrolled HC loading of the DPF.
System Interactions
SPN 1327 FMI 13 interacts with the following systems and may trigger cascading faults if not resolved promptly.
ECM communication — J1939 network faults can affect all connected modules
Engine protection — ECM may trigger derate to prevent damage
Aftertreatment — engine protection derates can affect regen strategy
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 1327 FMI 13 — 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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