Cummins QSB 6.7L SCR Filter 2011-2018: OEM 4387603

Engine-Matched NOx Conditioning for Cummins QSB 6.7L Engines (2011–2018)

What is it?
The Cummins QSB 6.7L SCR Filter (2011–2018), specified by OEM part number 4387603, is an exhaust aftertreatment component designed for Cummins QSB 6.7-liter diesel engines produced between 2011 and 2018. Installed as part of the Selective Catalytic Reduction (SCR) system, this filter helps condition exhaust gases so nitrogen oxides (NOx) can be more effectively reduced when interacting with Diesel Exhaust Fluid (DEF) in the SCR catalyst.

Why choose this SCR Filter?
This SCR filter is built to Cummins’ original specifications for the QSB 6.7L platform, offering precise fitment and reliable integration with DEF metering components, emissions sensors, and engine control systems. Over time, soot, ash, and other combustion byproducts can accumulate in the filter, diminishing its ability to properly condition exhaust gases. Choosing the correct OEM-specified filter helps support consistent exhaust behavior and steady NOx conditioning throughout the aftertreatment process.

Key Benefits
✅ Designed specifically for Cummins QSB 6.7L aftertreatment systems (2011–2018)
✅ Helps prepare exhaust gases for effective SCR NOx reduction
✅ Supports coordinated interaction with DEF dosing hardware and sensors
✅ Direct-fit replacement — no modifications required
✅ Built for heavy-duty exhaust environments

Applications
This SCR filter is suitable for medium- and heavy-duty vehicles equipped with Cummins QSB 6.7L engines manufactured from 2011 through 2018. It’s commonly found in tractors, vocational trucks, delivery rigs, and other commercial platforms where emissions compliance and regulated exhaust conditioning are part of daily use.

Installation Notes
Before servicing, make sure the exhaust and aftertreatment system has fully cooled to prevent burns or component damage. Remove the existing SCR filter and inspect nearby DEF lines, sensor connections, and mounting hardware for signs of soot buildup, wear, or damage. Install the replacement filter using proper seals and clamps to ensure a secure, leak-free fit. After installation, clear any stored system codes and verify correct SCR system behavior using diagnostic tools.

Final Thoughts
If your Cummins QSB 6.7L-equipped vehicle is showing NOx-related warnings, inconsistent emissions readings, or irregular aftertreatment behavior, replacing the SCR filter with the correct OEM-specified part can help restore steadier exhaust conditioning and more predictable system performance. The Cummins QSB 6.7L SCR Filter (OEM 4387603) plays an important role in managing regulated exhaust chemistry and supporting dependable engine operation across varied duty cycles.