5509100 | Genuine Cummins® Inlet Catalyst Module for ISC/ISL engines

1. Compatible Engines & Emissions Platforms

Part number is engineered for Cummins® heavy-duty engine platforms using the single-canister emissions assembly (Single Module™):

• Cummins® Engine Platforms: X15 (Performance & Efficiency Series), ISX15 (Late EPA 2017), L9, and ISL9 diesel engines.

2. Vehicle Fitment

This inlet module fits a broad array of Class 7 and Class 8 commercial vehicles:

• Freightliner: Cascadia 116/126, Coronado, and 122SD models.

• International / Navistar: LT Series, RH Series, LoneStar, and HX Series.

• Peterbilt: 579, 389, 567, and 520 models.

• Kenworth: T680, T880, W900L, and C500 models.

• Volvo / Western Star: 49X, 57X, and select Cummins-powered chassis.

1. What is it?

Part is a stainless steel inlet canister housing the Diesel Oxidation Catalyst (DOC). Positioned directly after the turbocharger downpipe, it receives raw exhaust gases from the engine and prepares them for the downstream Diesel Particulate Filter (DPF) and Selective Catalytic Reduction (SCR) stages.

2. Core Functions & Features

• Hydrocarbon Oxidation & Thermal Management: Converts unburned hydrocarbons (HC) and carbon monoxide (CO) into water vapor and carbon dioxide (CO2), creating the high exhaust temperatures required to initiate and maintain active DPF regeneration.

• Nitric Oxide Oxidation: Oxidizes nitric oxide (NO) into nitrogen dioxide (NO2), optimizing the NO2/NOx ratio required for efficient downstream soot oxidation and SCR performance.

• Integrated Sensor Ports: Precision-welded bosses host the upstream inlet NOx sensor, inlet Exhaust Gas Temperature (EGT) sensor, and DPF differential pressure tap.

1. Incomplete or Inability to Perform DPF Regenerations

• Symptom: The engine repeatedly attempts active DPF regeneration but fails to complete it, leading to a rapidly clogging сажевый/DPF filter and forced engine derate.

• Cause: A degraded or face-plugged Diesel Oxidation Catalyst (DOC) can no longer exothermically oxidize injected fuel to raise exhaust temperatures to the required threshold (~1,000°F / 550°C).

2. Active Check Engine Light (CEL) & Emission DTCs

The Engine Control Module (ECM) tracks temperature rises across the DOC substrate and flags catalytic conversion failures:

• Common Diagnostic Trouble Codes (DTCs):

  • SPN 3251 / FMI 0 or 15 (Aftertreatment DPF Differential Pressure - High / Very High)

  • SPN 4331 / FMI 18 (Aftertreatment 1 Diesel Oxidation Catalyst Efficiency - Below Normal)

  • SPN 4765 / FMI 2 (Aftertreatment 1 Diesel Oxidation Catalyst Intake Temperature - Data Erratic)

3. Excessive Soot Accumulation & High Exhaust Backpressure

• Symptom: Elevated turbocharger lag, loss of engine pulling power under heavy loads, and increased fuel consumption.

• Cause: Upstream contamination (from a leaking turbo seal or EGR cooler leak) forms a hardened crust over the DOC face, restricting total exhaust flow through the canister.

4. Excessive Raw Fuel Smoke or Odor during Regeneration

• Symptom: White or grey unburned fuel smoke and a strong raw diesel smell exiting the tailpipe when the engine initiates an active regeneration cycle.

• Cause: The catalyst substrate fails to ignite the raw diesel fuel injected by the dosing valve, allowing unburned fuel vapor to pass straight through the exhaust system.