Buy 5418490 - Genuine Cummins Outlet Catalyst Module - wisentpartscenter.com

Description

Cummins 4394687 Outlet Catalyst Module - Genuine Cummins SCR Outlet

The Cummins 4394687 is a genuine Cummins outlet catalyst module, the final catalyst stage in the aftertreatment assembly. It houses the SCR catalyst, where diesel exhaust fluid injected upstream reacts with NOx and converts it to nitrogen and water before the exhaust leaves the system.

Fitment & Specifications:

- Engine: Cummins B6.7
- Emissions: EPA 2017 and EPA 2021

Verify fitment with us before ordering to ensure the correct part for your application.

Purpose of the Part

By the time exhaust reaches the 4394687, soot has already been trapped by the DPF and DEF has already been sprayed and mixed into the stream. What is left to deal with is NOx. Ammonia carried in from the DEF adsorbs onto the catalyst surface inside this module and reacts with the NOx passing over it, releasing nitrogen and water vapour out the tailpipe. No moving parts, no electrical connection - the module either has active catalyst area or it does not.

Issue Symptoms / When to Replace

- The tell is DEF consumption rising while NOx conversion falls. The system doses harder to hit its target, the downstream NOx sensor keeps reporting a miss, and the ECM eventually logs a conversion efficiency fault and derates.

- Buses and medium duty chassis are harder on this module than highway trucks are. Stop and start routes hold exhaust temperature low, and sustained low temperature both slows the reaction and lets deposits build on the catalyst face.

- Before condemning it: a failed NOx sensor or a dosing unit that is under-delivering produces the same fault code and costs a fraction as much. Rule both out first.

Brand Information

Cummins has built diesel engines since 1919 and is one of the largest independent engine manufacturers in the world. Cummins Emission Solutions supplies the aftertreatment for the B6.7 across every chassis it powers, which is why the same outlet module appears under Navistar, Blue Bird, FCCC and Lion Bus part listings.

Installation Notes

Confirm the DEF dosing system is delivering correctly before fitting a new module. Installing catalyst behind a dosing fault repeats the failure.

How to Identify an OEM Part

Cummins logo and Cummins part number on the part. Confirm the number matches 4394687. Cummins catalogs the part as an Outlet Catalyst Module.

Why Buy 4394687 from Wisent Parts

  • ⏱️
    Fast shipping
    Orders before 12PM EST ship same business day.
  • 🛡️
    180-day warranty
    All parts covered from delivery date.
  • ↩️
    Easy returns
    30-day returns.
  • ✅
    Verify fitment
    Send VIN/ESN and we’ll confirm.

Shop with confidence

Warranty & Return Information
Warranty Information

Wisent Parts offers a 180-day warranty on all parts from the date of delivery. This warranty covers orders placed directly through our website. If a part fails during this period, we’re here to help - whether it’s a replacement, repair, or refund. For full details, refer to the Warranty page.

Return Information

Wisent Parts accepts returns within 30 days of delivery. All returns are subject to a restocking fee. To qualify, parts must be unused and in their original condition. For full return instructions and restocking fee details, please refer to the Returns page.