Cummins ISLG, QSG SCR Outlet Catalyst Module 2015-2020: OEM 4377790

Supporting Reliable SCR Aftertreatment in Cummins ISLG and QSG Engines (2015–2020)

What is it?
The Cummins ISLG, QSG SCR Outlet Catalyst Module, identified by OEM 4377790, is an exhaust aftertreatment component designed to support Selective Catalytic Reduction (SCR). This system uses Diesel Exhaust Fluid (DEF) to help convert nitrogen oxides (NOx) into nitrogen and water vapor through a controlled chemical reaction. The outlet catalyst module helps complete the exhaust treatment process before gases exit the exhaust system.

Why choose this SCR Outlet Catalyst Module?
Cummins ISLG and QSG engines require properly functioning aftertreatment components to maintain effective emissions control. OEM 4377790 is intended for compatible 2015–2020 applications, helping maintain proper integration with the existing SCR system.

Continuous exposure to high exhaust temperatures, DEF deposits, contamination, and repeated thermal cycles can gradually affect catalyst activity. Problems with DEF dosing, exhaust temperature regulation, or upstream aftertreatment components may also contribute to premature deterioration.

Possible signs of SCR catalyst issues include emissions-related fault codes, elevated NOx readings, DEF system warnings, engine warning lights, or irregular aftertreatment operation. Installing the correct application-matched module helps restore the intended exhaust treatment process.

Key Benefits
✅ Designed for compatible Cummins ISLG and QSG applications (2015–2020)
✅ Supports effective Selective Catalytic Reduction treatment
✅ Helps reduce nitrogen oxide (NOx) emissions
✅ Supports conversion of NOx into nitrogen and water vapor
✅ Integrates with compatible SCR and DEF aftertreatment components
✅ Designed for demanding diesel exhaust operating conditions

Applications
This SCR Outlet Catalyst Module is intended for compatible Cummins ISLG and QSG engine applications from 2015 through 2020. Depending on the engine configuration, these applications may include industrial equipment, commercial vehicles, construction machinery, and other heavy-duty equipment. Because emissions systems can differ between engine models and fuel types, confirm OEM number 4377790 along with the engine serial number and aftertreatment configuration before installation.

Installation Notes
Allow the engine and exhaust system to cool completely before beginning installation. Inspect the DEF injector where equipped, NOx sensors, temperature sensors, exhaust piping, clamps, seals, and surrounding aftertreatment components for contamination, deposits, leaks, or damage. Identify and correct any underlying exhaust or emissions-system issues before installing the replacement. After installation, inspect for exhaust leaks, clear applicable diagnostic codes, and verify aftertreatment operation using suitable diagnostic equipment.

Final Thoughts
Effective exhaust treatment depends on properly matched components working together throughout the aftertreatment system. The Cummins ISLG, QSG SCR Outlet Catalyst Module (OEM 4377790) helps maintain consistent emissions control and dependable exhaust treatment for compatible 2015–2020 applications.