5418652 | Genuine Cummins® Outlet Catalyst Module for ISB/QSB

1. Compatible Engine Platforms & Applications

Part number is used on medium-duty commercial trucks, school buses, and industrial/off-highway equipment equipped with Cummins Single-Module™ aftertreatment assemblies:

• Engine Series: Cummins® ISB6.7, QSB6.7, and B6.7 (EPA17 and industrial Tier 4 Final platforms).

• Commercial Truck & Bus Brands: Freightliner Custom Chassis, International / Navistar (Durastar / MV Series), Blue Bird, Thomas Built Buses, and Ford F-650 / F-750 equipped with Cummins B6.7/ISB engines.

• Industrial & Off-Highway Equipment: Construction, agricultural, and power generation machinery (Komatsu, Hyundai, JCB, Case) powered by Cummins QSB6.7 engines.

1. What is it?

Part 5418652 acts as the downstream output section of the single-module aftertreatment system used primarily on EPA17 6.7L ISB, QSB, and B6.7 engines. Positioned right after the Diesel Particulate Filter (DPF) and DEF injection nozzle, it performs the final chemical cleanup of harmful exhaust gas emissions.

2. Core Functions

• NOx Reduction (SCR): Combines atomized Diesel Exhaust Fluid (DEF/AdBlue) with incoming exhaust gases over precious metal ceramic substrates to convert toxic nitrogen oxides into harmless nitrogen gas and water vapor.

• Ammonia Slip Suppression (AMOX): Includes a secondary catalytic stage on the exit end to eliminate unreacted ammonia fumes before exhaust exits the tailpipe.

• Sensor Monitoring: Houses built-in ports for downstream $\text{NO}_x$ and temperature sensors, sending real-time efficiency data to the Engine Control Module (ECM).

• High Thermal Resistance: Constructed with heavy-gauge stainless steel to endure vibration, thermal expansion, and intense exhaust temperatures.

1. Active NOx Conversion Fault Codes

• Symptom: Check Engine or Stop Engine light illuminated with active codes: FC3582 / FC3547 (Aftertreatment 1 SCR Conversion Efficiency Low) or FC2771 (Aftertreatment 1 Outlet $\text{NO}_x$ Sensor High).

• Cause: Degradation or poisoning of the active catalytic washcoat prevents the module from neutralizing nitrogen oxides down to required thresholds.

2. Severe Engine Power Derate & Speed Limits

• Symptom: Engine power is capped, torque is reduced by up to 25–40%, or maximum vehicle speed is restricted (e.g., 5 mph / 8 km/h derate).

• Cause: The Engine Control Module (ECM) enforces mandatory safety derates when NOx conversion efficiency drops below legal limits for prolonged operating cycles.

3. DEF Face-Plugging & Backpressure Spikes

• Symptom: Sluggish acceleration, increased fuel consumption, or fault code FC3575 (SCR Catalyst Intake Face Plugging).

• Cause: Crystallized Diesel Exhaust Fluid (DEF/AdBlue) accumulates on the intake face of the ceramic catalyst brick, choking off exhaust flow.

4. Physical Substrate Damage & Internal Rattling

• Symptom: Metallic rattling or clunking noises coming from inside the aftertreatment canister during engine idle, or visible cracks/soot tracks around housing clamps.

• Cause: Thermal stress or extreme chassis vibration breaks or detaches the internal ceramic substrate from its mounting mat.

5. Excessive DEF Consumption Without Emissions Reduction

• Symptom: High DEF consumption rates without any improvement in NOx conversion readings.

• Cause: Oil or soot carryover from turbocharger or engine blow-by coats the catalyst surface, masking it from reacting with the injected DEF.