Spn 4364 Fmi 31 Cummins (2024)

FAQs

What is the code FMI 31 on a Cummins SPN 4364? ›

This fault code indicates that the nox emissions are not being reduced enough by the SCR catalyst. There are many possible causes for this fault code including:Degraded DEF fluid. A faulty SCR catalyst.

In summary, SPN 4364 FMI 18 is an engine error code related to the aftertreatment system of a diesel engine. It can indicate a variety of issues, ranging from a faulty NOx sensor to a malfunctioning DEF system.

Description This code sets when the Aftertreatment Control Module (ACM) detects that the Selective Catalyst Reduction (SCR) NOx Conversion efficiency is low.

SPN 521049/FMI 31

Description This Code Sets When There is a Code Present for the Diesel Exhaust Fluid (DEF) Tank Level, DEF Dosing Unit, DEF Pump, NOx Sensors, Blocked DEF Line, DEF Quality, NOx Efficiency, Selective Catalyst Reduction (SCR) Harness and/or SCR Sensor.

FAILURE MODE IDENTIFIERS (FMI) Now that we have defined MID (The component) and PID (types of data), we can talk about Failure Mode Identifiers (FMI). Every diagnostic trouble code (DTC) that you find will have an FMI.

SPN is short for suspect parameter number. It identifies which electrical circuit, part or component of your truck isn't working properly. FMI stands for failure mode identifier—this part of the fault code tells you what type of problem your truck has.

Using a code reader tool, connect to the ECM and find the “fault codes” tab. The displayed codes can generally be clicked on one by one. Another option is to select “erase all faults” and then follow the onscreen instructions. At the end of the procedure, the ignition key should be turned off.

This measurement happens between your inlet and outlet NOx sensors and it's called your SCR NOx efficiency. If the SCR NOx efficiency goes below 70%, then these fault codes get set “Active.” The only way you can clear these codes is by doing a forced regen with the SCR NOx efficiency above 70%.

Cummins ReCon® NOx sensors are the smart, low-cost replacement choice to help keep your engine's aftertreatment system operating normally. When a NOx sensor fails it can prompt multiple fault codes; capping the engine output, placing it in limp mode. 1.

SPN stands for Suspect Parameter Number. It's a diagnostic trouble code that provides detailed information about specific faults detected by the vehicle's ECU, making it easier to identify and address issues within the vehicle's electronic systems.

What is the NOx sensor behind the SCR catalyst? ›

The sensor located upstream of the SCR catalyst directly measures the engine-out NOx gas concentration, which helps determine the optimum amount of urea injection. The NOx sensor downstream of the SCR catalyst is used to monitor the performance of the catalyst.

This fault code is for your aftertreatment system indicating poor NOx conversion efficiency. The potential causes are listed below but this will eventually cause your power to be cut back by the ECM if this fault code is ignored and the truck is continued to be driven.

The FMI may indicate that a problem with an electronic circuit or an electronic component has been detected. The FMI may also indicate that an abnormal operating condition has been detected. The codes are displayed in the form “SPN – FMI”.

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Failure Mode Indication (FMI), as part of the J1939 standard used in heavy-duty vehicles, functions by closely monitoring system components. When a fault occurs, FMI generates a precise code that identifies the specific nature of the issue, much like an advanced version of a 'check engine' light.

Long story short, these fault codes mean that the efficiency in the aftertreatment system, aka the 1-Box, is not operating within the required threshold (70%). This measurement happens between your inlet and outlet NOx sensors and it's called your SCR NOx efficiency.

An aftertreatment system is a method or device for reducing harmful exhaust emissions from internal-combustion engines. In other words, it is a device that cleans exhaust gases to ensure the engines meet emission regulations.

4364 1 fault occurs when the outlet Nox is higher than expected. This is, be caused by either a faulty Nox sensor or poor quality DEF contaminating the system and potentially causing problems or failure with your scr and after treatment components.