DEF Dosing Injector Valve for Caterpillar 320E / 336E / 966M - Replaces 424-4205 - OEM Denoxtronic Injector

OEM DEF Dosing Injector — Solve Your Derate Codes

Solve your "Low DEF Pressure" or "Reductant Metering" fault codes. This is the Genuine OEM DEF Dosing Module for Caterpillar Tier 4 Interim and Final engines — the exact same unit that Cat re-boxes and sells as their own for nearly $1,000.

The Problem

Your DEF (Diesel Exhaust Fluid) injector sits directly on the exhaust pipe, spraying urea into the exhaust stream. Because it is exposed to extreme exhaust heat and crystallizing fluid, it fails in two ways:

• Clogged: DEF crystallizes inside the nozzle, blocking the spray pattern
• Electronic Failure: The metering valve solenoid burns out from heat cycling

When the dosing injector fails, the SCR system cannot reduce NOx emissions. The ECU detects this and puts your machine into Derate Mode — first reducing power by 25%, then eventually forcing a complete shutdown.

The Solution

Replace the failed dosing injector with this Genuine OEM Denoxtronic 2.2 unit. It's the identical part that came on your machine from the factory. Caterpillar does not manufacture DEF injectors — they purchase them from the original equipment supplier and re-label them. The "Denoxtronic 2.2" marking is visible on the black plastic housing.

Installation Note

This is the coolant-cooled version. Please ensure you clamp your coolant lines before removal to minimize fluid loss. The coolant circuit prevents the DEF from crystallizing inside the injector during operation.

Technical Specifications

• Cat Part Number: 424-4205 (also replaces 460-9256, 383-9377)
• Perkins Part Number: T401183
• Manufacturer: Original Equipment Supplier (Germany)
• OES Designation: Denoxtronic 2.2
• System: Denoxtronic 2.2 (Coolant Cooled)
• Condition: Brand New, Genuine OEM

Compatible Caterpillar Equipment

Excavators

• Cat 320E / 320F Excavator (C6.6 Engine)
• Cat 323E / 323F Excavator (C7.1 Engine)
• Cat 324E Excavator (C7.1 Engine)
• Cat 329E / 329F Excavator (C7.1 Engine)
• Cat 336E / 336F Excavator (C9.3 Engine)

Wheel Loaders

• Cat 950K / 950M Wheel Loader
• Cat 962K / 962M Wheel Loader
• Cat 966M Wheel Loader
• Cat 972M Wheel Loader

Motor Graders

• Cat 12M Series 2 Motor Grader
• Cat 140M Series 2 Motor Grader

This dosing injector fits all Caterpillar machines equipped with the Denoxtronic 2.2 emissions system. If your parts manual lists 424-4205, 460-9256, or 383-9377, this is the correct replacement.

Why Buy From Trenchwell?

• Save 30%+ vs Dealer: Cat dealers charge $860–$980 for this injector. We sell the identical Genuine OEM part for $589.
• Genuine OEM Quality: This is NOT an aftermarket clone. The "Denoxtronic 2.2" marking on the housing confirms authenticity. Accept no substitutes for your emissions system.
• Complete Emissions Fix: If your SCR system has multiple codes, pair this with our OEM NOx Sensor and DEF Pump Filter Kit for a complete repair at a fraction of dealer cost.

Frequently Asked Questions

My DEF injector is clogged. Can I clean it instead of replacing it?
You can try soaking the nozzle tip in warm distilled water, but if the metering valve has failed electronically or the internal passages are crystallized, cleaning will not restore proper function. A new OEM unit is the reliable fix.

Do I also need to replace the DEF pump filter?
Yes, we strongly recommend it. When the dosing injector fails, it is often because the pump filter was dirty, allowing contaminated DEF to reach the injector. Replacing the filter kit prevents the new injector from failing prematurely.

Is this the same part Perkins sells as T401183?
Yes. Caterpillar and Perkins use the same Denoxtronic 2.2 dosing module. The Cat 424-4205 and Perkins T401183 are the identical OEM part.