CAT Caterpillar C4.4, C3.6 DEF Head Unit

Emissions Assurance for CAT C4.4 / C3.6 – OEM DEF Head Unit (5913429)

What is it?
The OEM 5913429 DEF Head Unit is a factory-specified header assembly designed for Caterpillar C4.4 and C3.6 diesel engines equipped with SCR (Selective Catalytic Reduction) and DEF (Diesel Exhaust Fluid) systems. Mounted at the top of the DEF tank, this unit includes sensors that monitor fluid level and temperature, enabling precise DEF dosing and reliable emissions control.

Why choose this OEM DEF Head Unit?
This unit is manufactured to Caterpillar’s original specifications, ensuring proper sensor calibration, tight sealing, and seamless compatibility with the engine’s emissions control systems. Using the genuine component helps avoid DEF system malfunctions, sensor faults, leaks, and erroneous warnings often seen with lower‑quality aftermarket replacements.

Key Benefits
 ✅ Direct-fit for CAT C4.4 and C3.6 SCR systems
 ✅ Accurate monitoring of DEF fluid level and temperature
 ✅ Proper sealing to prevent leaks and preserve DEF integrity
 ✅ Compatibility with factory diagnostics and SCR control logic
 ✅ Rugged construction built for heat, vibration, and operational stress

Applications
Ideal for servicing or upgrading equipment powered by CAT C4.4 or C3.6 engines that use DEF-based emission control. Common in mobile machinery, industrial units, and construction equipment where emissions compliance and DEF system reliability are essential.

Installation Notes
Have a certified technician perform installation. Begin by depressurizing or isolating the DEF system to prevent fluid loss or sensor damage. Clean the mounting surfaces and inspect the DEF tank opening for debris or corrosion. Replace any worn or damaged O‑rings or gaskets. Mount the head unit in place and torque the fasteners to OEM specifications. Once installed, verify sensor readings via diagnostics, check for leaks, and clear any DEF or SCR system fault codes to confirm proper operation.

Final Thoughts
If your CAT C4.4 or C3.6 engine is encountering DEF system warnings, erratic readings, or embarrassingly unusable SCR behavior, replacing the head unit with the OEM 5913429 DEF Head Unit restores accurate sensor function and reliable emissions system integrity. With factory-level performance and compatibility, it's a dependable solution to keep your machines clean and compliant.