Description: Inlet Catalyst Module For Cummins EPA17 Automotive 6.7 L ISB/QSB
Condition: New
Brand: Cummins®
Part Number: 4394859CUM
Vehicle Fitment 4394859CUM:
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Engine Platforms:
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Heavy-Duty: Cummins ISX15, X15, and ISX12.
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Medium-Duty: Cummins ISB6.7 and ISL9/L9.
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Emissions Standards: Primarily used in systems meeting EPA10, EPA13, and EPA17 regulations.
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Primary Vehicle Applications:
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Linehaul Trucks: Kenworth T680, Peterbilt 579, Freightliner Cascadia, International LT.
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Vocational & Specialized: Dump trucks, cement mixers, and fire trucks (E-One, Pierce).
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Buses: Transit buses and motorcoaches (New Flyer, Gillig, MCI).
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The Inlet Catalyst Module 4394859CUM is the first section of a modern diesel aftertreatment system, housing the Diesel Oxidation Catalyst (DOC). In a modular setup, the exhaust gas enters this unit before passing into the Diesel Particulate Filter (DPF)
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Oxidation: It contains a ceramic honeycomb structure coated with precious metals that trigger a chemical reaction. It converts carbon monoxide (CO) and unburnt fuel (hydrocarbons) into CO2 and water.
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Heat Generation: Its most vital role is to support the "regeneration" process. It oxidizes fuel injected into the exhaust stream to create the high temperatures (over 550°C) needed to burn off soot in the downstream DPF.
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NO conversion: It converts Nitric Oxide (NO) into Nitrogen Dioxide (NO2), which acts as a catalyst to help the DPF clean itself naturally during normal driving (passive regeneration).
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Housing: It provides the mounting points for the first set of temperature and pressure sensors that monitor the health of the entire emissions system.
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Signs of Faulty 4394859CUM:
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Face Plugging: If you see a thick layer of black soot or white/grey ash on the inlet face of the catalyst, the module is "plugged." This restricts exhaust flow, leading to high backpressure, turbo lag, and increased fuel consumption.
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Low Temperature Gain (Regen Failures): During a parked regeneration, the ECM monitors the temperature rise across the DOC. If the outlet temperature doesn't reach the required threshold (typically 1000°F / 540°C), the DOC is likely "poisoned" or its precious metal coating has degraded.
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Oil or Coolant Soaking: If a turbo seal fails or an EGR cooler leaks, the DOC becomes "contaminated." You will notice blue or white smoke coming from the exhaust. A soaked DOC cannot generate heat and often cannot be cleaned—it must be replaced.
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Thermal Damage (Melting): If too much raw fuel reaches the DOC (due to a leaking injector), it can cause an uncontrolled "torch" effect. This melts the internal ceramic honeycomb, which can sometimes be seen as a "sinkhole" or melted center when looking inside the unit.
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Fault Codes:
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Manufacturer information
Cummins® is a worldwide leader in the production of engines, agricultural components, and other power-generating devices for various industries, including medium and heavy duty trucks, light commercial vehicles, buses, agriculture, and construction. Founded in 1919, this company stays true to its mission of making people's lives better by continuously improving its product line-up and introducing new solutions for a more prosperous world. Its core values—integrity, diversity and inclusion, excellence, caring, and teamwork—are what make it a successful company today—a worldwide leader with a network of more than 600 company-owned and independent distributors and almost 6,000 dealers in approximately 190 countries.
Warranty
First Truck Parts offers a 365-days warranty for all types of parts and in any condition. The warranty applies only to buyers who have placed an order on our website.
