5418125 - Genuine Cummins Decomposition Reactor - 2 - wisentpartscenter.com

Description

Cummins 5418125 Decomposition Reactor - Genuine Cummins Decomposition Reactor / Mixer for EPA17 B6.7 and L9 Engines

The Cummins 5418125 is the genuine decomposition reactor/mixer for the SCR aftertreatment system. DEF is injected into it and breaks down and mixes into ammonia in the exhaust stream before the SCR catalyst, so the system can convert NOx.

Key Functions:

- Mixes and decomposes injected DEF into ammonia ahead of the SCR catalyst
- Supports NOx conversion for EPA17 emissions compliance

Fitment & Specifications:

- Application: Cummins EPA17 B6.7 (ISB/QSB 6.7L), L9 - CM2350 / CM2450 (confirm by engine)
- Part: 5418125 decomposition reactor / mixer

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

Purpose of the Part

It's where DEF turns into usable ammonia. The dosing injector sprays urea into the reactor, and the mixer and heat break it down and blend it evenly into the exhaust before the SCR catalyst. If it's clogged with deposits or leaking, DEF doesn't mix right and the SCR can't clean up NOx - which throws faults and derates.

Issue Symptoms / When to Replace

- SCR / DEF aftertreatment fault codes, poor NOx conversion
- DEF crystallization or deposits in the reactor
- Exhaust leak at the reactor joints
- Derate from unresolved SCR faults

Pull the active codes with Cummins INSITE

Brand Information

A genuine Cummins 5418125 is built to the exact SCR spec for these EPA17 engines, so DEF decomposes and mixes the way the system needs to pass emissions - which off-brand reactors with poor mixing geometry can't reliably do. Cummins builds engines, aftertreatment, and power systems worldwide.

Installation Notes

- Mixer element only - confirm it's what your repair needs and transfer/reuse the rest of the reactor and dosing hardware.
- Check for DEF crystallization/deposits on the mixer and in the reactor while you're in there.

How to Identify an OEM Part

Genuine Cummins reactors have the Cummins part number and a serial number carved/stamped into the part - match the carved PN to your listing.

Why buy 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.