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

Emissions Confidence for Detroit‑Powered Freightliners: OEM DEF Head Unit

What is it?
The OEM DEF Head Unit is the factory‑specified header assembly for Freightliner chassis powered by Detroit engines (DD5, DD8, DD13, DD15). It mounts onto the DEF tank and houses the sensors responsible for monitoring fluid level, temperature, and ensuring the proper operation of the SCR (Selective Catalytic Reduction) system that reduces NOₓ emissions.

Why choose this OEM DEF Head Unit?
This genuine unit is built to Detroit’s original engineering standards, guaranteeing proper sensor calibration, precise mounting, effective sealing, and full integration with the vehicle’s emission control electronics. Using the correct OEM part helps avoid system faults, false warnings, fluid leaks, and SCR malfunctions that often arise from substandard or aftermarket replacements.

Key Benefits
 ✅ Direct-fit for Freightliner units with Detroit DD5, DD8, DD13, DD15 engines
 ✅ Accurate monitoring of DEF fluid level and temperature
 ✅ Proper sealing to prevent leaks, contamination, and fluid loss
 ✅ Supports factory diagnostics and emission system integrity
 ✅ Durable design to withstand thermal, vibrational, and road conditions

Applications
Used in Freightliner trucks equipped with Detroit engines across medium- and heavy-duty classes that require SCR/DEF aftertreatment. This unit is critical in vocational, regional, and over-the-road applications where emission compliance and reliable DEF system performance are mandatory.

Installation Notes
Have an experienced technician perform the installation. Depressurize or disable the DEF system before removal. Clean the mounting surfaces and inspect for damage or residue. Replace all O‑rings or gaskets. Install the new head unit torqued to OEM specifications. After installation, verify sensor readings, ensure proper system behavior, and clear any DEF/SCR-related fault codes.

Final Thoughts
If your Freightliner with a Detroit engine is facing DEF sensor warnings, erratic fluid level behavior, or emission system errors, replacing the head unit with the correct OEM model restores system stability, sensor accuracy, and emissions compliance—helping you stay on the road with confidence.