Just got SPN 4364 FMI 18 code (2024)

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Just got SPN 4364 FMI 18 code? ›

SPN 4364 FMI 18 Causes

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

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.

Description This Code Sets When the Aftertreatment Control Module (ACM) Detects Poor Selective Catalyst Reduction (SCR) NOx Conversion Efficiency. Check as follows: 1. Refer to section "SPN 4364/FMI 17 - GHG 17" and follow the diagnostic procedure.

The 4364 fault is for scr cat efficiency. This fault is present whenever the scr can not treat the nox levels. The very first thing is to check for any charge air leaks, check for any obvious ex or egr leaks. Make sure the engine does not have extended crank.

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. Symptoms include the illumination of the check engine light and potential engine derate mode.

Mechanical damage – long-term driving with a damaged NOx sensor may lead to failure of other parts of the exhaust system, such as the catalytic converter. In extreme cases, this may pose a threat to driving.

This fault code is for low fuel delivery pressure during cranking. Replace your fuel filters and look for any fuel leaks or restrictions between the fuel tank and fuel pump. Low fuel pressure can also be caused by a faulty fuel pump, injectors,or pressure regulator.

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.

SCR NOX conversion measures the efficiency of this process, calculated by the Engine Control Module (ECM) via inlet and outlet NOX sensor readings. High conversion rates signify effective emission reduction, while low rates indicate issues needing attention.

How do you diagnose a faulty NOx sensor? ›

In modern diesel engines, NOx sensors are often placed downstream of diesel particulate filters and selective catalytic reduction (SCR) systems to further reduce NOx emissions. Overall, NOx sensors play a vital role in reducing harmful emissions from internal combustion engines and meeting environmental regulations.

An oxides of nitrogen sensor is used to monitor the levels of oxides of nitrogen that a vehicle emits to ensure it is compliant with emissions regulations. Oxides of nitrogen (otherwise known as NOx) are pollutants that have both environmental and health impacts.

A NOx sensor is placed in exhaust systems to observe nitrogen oxide (NOx) levels in the exhaust. On most systems, there are usually two NOx sensors. There is one right after the exhaust manifold and the second after the selective catalytic reduction (SCR) system to monitor SCR efficiency.

Put simply, the NOx Sensor is responsible for measuring the vehicles' NOx (Nitrogen Oxide) levels produced following the combustion cycle. NOx emissions are found in an engine due to higher in-cylinder temperatures.

What is a NOx levels sensor? A nitrogen oxide sensor is a high-temperature device built with intricate technology to detect nitrogen oxides in the air, ammonia concentrations, and emissions regulations in combustion environments, such as in the exhaust of a truck with a diesel motor.

The first one is water in the exhaust system, a by-product of combustion and catalytic conversion, can damage the NOx sensor. NOx Sensor failure also relates to excess fuel entering the exhaust system, injector fouling, injector leaking or engine misfire are all things that can lead to sensor failure.

If the NOX sensor fails, the engine computer will register a fault and the engine starts stalling slightly. The check engine light will also come on. In many cases, the NOX sensor is broken.

One of the most common NOx sensor failures is high fuel consumption. This can be caused by an oxygen sensor not reading correctly, which causes your Cummins engine to run lean. A lean mixture will burn more fuel, leading to increased emissions.

ENGINE MISFIRE AND SOOT BUILD-UP

An engine's misfiring can be caused by a number of things. However, a sudden engine misfire could indicate a broken NOx sensor. When there is insufficient oxygen present during burning, this occurs.