Freightliner Detroit DD5, DD8, DD13, DD15 DEF Head Unit

Precision Emissions for Detroit‑Powered Freightliner – OEM DEF Head Unit (04‑30774‑004)

What is it?
The OEM 04‑30774‑004 DEF Head Unit is a factory DEF system component designed for Freightliner trucks equipped with Detroit DD5, DD8, DD13, or DD15 engines. This header assembly attaches to the DEF tank and contains sensors that monitor fluid level and temperature, helping to regulate SCR (Selective Catalytic Reduction) system performance and emissions compliance.

Why choose this OEM DEF Head Unit?
Engineered to meet Detroit and Freightliner factory standards, this unit ensures accurate sensor output, correct sealing, and plug‑and‑play compatibility with existing DEF system wiring and diagnostics. Using the genuine component helps avoid common DEF system issues—such as warning lights, faulty sensor readings, leaks, or system faults—that can arise from off‑spec replacements.

Key Benefits
 ✅ Direct OEM fit for Freightliner models with Detroit DD5 / DD8 / DD13 / DD15 engines
 ✅ Accurate monitoring of DEF fluid level and temperature
 ✅ Sealed design to prevent leaks and maintain fluid purity
 ✅ Fully compatible with factory emission controls and diagnostics
 ✅ Rugged construction built to handle highway and vocational service

Applications
Intended for Freightliner trucks powered by Detroit engines across various classes—from medium-duty to heavy-duty—this DEF Head Unit is essential for applications that require SCR/DEF aftertreatment systems, such as regional delivery, vocational duty, refuse, and highway freight.

Installation Notes
Installation should be handled by a qualified technician. Start by depressurizing or isolating the DEF system. Clean the DEF tank opening and inspect the mounting surface. Replace any worn O‑rings or gaskets. Install the head unit following OEM torque specifications, then use diagnostic tools to verify sensor output, check for leaks, and clear any DEF or SCR fault codes to confirm proper operation.

Final Thoughts
If your Freightliner is showing DEF system warnings, erratic level readings, or sensor faults, the OEM 04‑30774‑004 DEF Head Unit restores accurate performance and system stability. With factory-level design and compatibility, it helps ensure your emission controls operate as intended—keeping your fleet compliant, reliable, and on the road.