5418481 | Genuine Cummins® Inlet Catalyst Module

1. Compatible Engines & Emissions Systems

Part number 5418481 is designed for Cummins® medium-duty diesel engines equipped with Single Module™ or modular Aftertreatment Systems (EPA 2017 / Euro 6 / Stage V standards):

• Cummins® Engine Platforms: B6.7, ISB6.7, L9, and ISL9 CM2350 / CM2450 series engines.

• Emissions Standard: EPA 2017+ emissions compliant aftertreatment configurations.

2. Vehicle & Equipment Fitment

• Medium & Heavy-Duty Trucks: Freightliner® (M2 106, 108SD), International®/Navistar® (MV Series, HV Series), Ford® (F-650, F-750 with 6.7L Cummins), and Peterbilt® / Kenworth® medium-duty trucks (Models 337, 348, T270, T370).

• Buses & Transit: Blue Bird®, Thomas Built Buses®, and IC Bus® school and commercial transit vehicles.

• Vocational & Specialty Equipment: Fire apparatus, refuse trucks, dump trucks, and sweeper platforms powered by Cummins B6.7 or L9.

1. What is it?

Part is the inlet section of the Selective Catalytic Reduction (SCR) and Diesel Particulate Filter (DPF) assembly. Located directly downstream of the engine turbocharger exhaust pipe, it houses the Diesel Oxidation Catalyst (DOC) or primary decomposition chamber where Diesel Exhaust Fluid (DEF/AdBlue®) is injected, atomized, and thoroughly mixed with hot exhaust gases.

2. Core Functions & Technical Features

• Hydrocarbon Oxidation & NO-to-NO₂ Conversion: Utilizes a precious-metal-coated ceramic honeycombed substrate to oxidize unburned hydrocarbons (HC) and carbon monoxide (CO), converting NO to NO₂ to facilitate passive DPF regeneration.

• Exhaust Flow Uniformity & Heat Distribution: Features internally tuned flow-diffusers that evenly distribute raw exhaust gas and heat across the full face of the downstream filter substrate, preventing localized hot spots.

• Integrated DEF Dosing & Mixing Port: Includes dedicated mounting bosses for the DEF injector nozzle and internal mixer blades designed to fully vaporize urea into ammonia (NH₃) without forming harmful crystalline deposits.

• Heavy-Gauge Stainless Steel Housing: Built with high-grade, heat-corrosion-resistant stainless steel to endure severe thermal cycling and road vibration in commercial service.

1. Active Aftertreatment Check Engine Lights & Fault Codes

The Engine Control Module (ECM) triggers diagnostic trouble codes (DTCs) when it detects improper oxidation efficiency, high exhaust backpressure, or DEF dosing errors:

• Common Fault Codes:

  • SPN 3251 / FMI 0, 2 (DPF Differential Pressure - High / Erratic)

  • SPN 4364 / FMI 18 (SCR NOx Conversion Efficiency - Below Normal)

  • SPN 3058 / FMI 10, 18 (EGR System / Aftertreatment System Degradation)

  • SPN 3556 / FMI 18 (Aftertreatment Hydrocarbon Dosing / Fuel Injected into Exhaust Error)

2. Frequent or Failed DPF Regenerations

• Symptom: The truck attempts active DPF regeneration far more often than normal, or active regenerations fail to complete and log time-out errors.

• Cause: Degraded precious-metal coating inside the catalyst fails to oxidize hydrocarbons effectively, preventing the exhaust gas from reaching the high temperatures (1,000°F / 540°C+) required to burn off soot in the DPF.

3. Excessive Crystallized DEF / Urea Deposit Buildup

• Symptom: White, chalky crystalline buildup clogs the mixer section or coats the inlet face of the catalyst, restricting exhaust flow.

• Cause: Internal flow-diffuser damage or failed mixing geometry preventing the injected DEF from fully atomizing and vaporizing into ammonia gas (NH₃).

4. Loss of Engine Power & Low Turbo Boost (High Backpressure)

• Symptom: The engine feels sluggish under load, fuel economy drops, or the ECM forces an engine power de-rate.

• Cause: Melted, face-plugged, or cracked ceramic substrates block the exhaust passage, causing excessive exhaust backpressure that chokes the turbocharger.