4353812 | Genuine Cummins® Inlet Catalyst Module EPA13 6.7L ISB/QSB

• School Buses: This is a primary application. Fits most Blue Bird (Vision/All American) and Thomas Built (Saf-T-Liner C2) buses manufactured between 2013 and 2021.

• Medium-Duty Trucks: Widely used in Freightliner M2 106 and International MV/Durastar models.

• Vocational Vehicles: Found in Kalmar Ottawa and Capacity yard spotters/terminal tractors.

• Step Vans: Common in Freightliner Custom Chassis (FCCC) MT45/MT55 walk-in vans used by delivery services like UPS or FedEx.

Technical Specifications

• Engine: Cummins ISB 6.7 / QSB 6.7.

• Emissions Level: EPA 2013, EPA 2017.

• Module Role: This is the DOC (Diesel Oxidation Catalyst), which sits upstream of the DPF. It features the inlet pipe that connects to the engine's turbo downpipe.

1. Oxidation: It uses precious metals (like platinum or palladium) to chemically convert carbon monoxide and unburnt hydrocarbons into carbon dioxide and water.

2. Heat Generation: It plays a critical role during "Active Regeneration." By oxidizing diesel fuel injected into the exhaust stream, it raises the exhaust temperature to approximately 1000°F (538°C), which is necessary to burn the soot out of the following DPF (Diesel Particulate Filter).

3. NO2 Creation: It converts Nitrogen Oxide (NO) into Nitrogen Dioxide (NO2), which helps the downstream SCR (Selective Catalytic Reduction) system work more efficiently.

Physical Appearance: It is a stainless steel cylinder. One side features a fixed Inlet Pipe (usually with a 4-bolt flange) that connects to the turbocharger's downpipe. The other side is a wide, open flange that clamps directly to the DPF.

• Incomplete or Failed Regenerations: The most common sign. If the catalyst is "poisoned" (coated in oil or coolant) or degraded, it cannot reach the 1000°F (538°C) needed to clean the DPF. You will see "Regen Incomplete" messages.

• Rapid DPF Soot Loading: Because the DOC isn't helping burn off soot passively or actively, the DPF will clog much faster than usual, leading to frequent requests for parked regenerations.

• Low Temperature Fault Codes: You will likely see Cummins codes such as FC1691 (Catalytic Converter Efficiency Low) or FC2639 (Manual Regen Required - Soot Load High).

• Face Plugging: If you remove the module and look inside the inlet pipe, you might see a buildup of soot or "gunk" on the front face of the catalyst. This restricts exhaust flow.

• Excessive Smoke: If the DOC is damaged, you may notice white smoke (unburnt fuel) coming from the exhaust during an attempted regeneration because the catalyst isn't hot enough to oxidize the fuel.

• Engine Derate: Eventually, the ECM will detect the high backpressure or low efficiency and limit the engine's speed and torque to prevent further damage.