Cummins ECO-FIT Cummins ISB 6.7L, B6.7 DEF Head Unit

Emission Control Restored for Cummins ISB 6.7L / B6.7: OEM DEF Head Unit (5511561)

What is it?
The OEM 5511561 DEF Head Unit is a factory-spec DEF (Diesel Exhaust Fluid) header assembly used with Cummins ECO‑FIT ISB 6.7L and B6.7 engines. This unit controls the DEF fluid delivery and includes sensors that monitor DEF level, temperature, and integrity—ensuring your aftertreatment system works correctly under emissions regulations. 

Why choose this OEM DEF Head Unit?
Built to Cummins’ ECO‑FIT and original OEM specifications, this DEF Head Unit provides accurate fitment, proper sealing, and full compatibility with SCR and DEF system controls. It helps avoid diagnostic warnings, fluid leaks, or system faults often linked to lower‑quality replacements.

Key Benefits
 ✅ Designed specifically for Cummins ISB 6.7L / B6.7 ECO‑FIT engines
 ✅ OEM‑grade sensors ensure accurate DEF level and temperature readings
 ✅ Proper sealing integrity to prevent DEF leaks and contamination
 ✅ Helps maintain emission system compliance and avoid warning codes
 ✅ Built for rugged, long‑term duty with warranty protection included

Applications
Ideal for medium‑duty trucks, service fleets, transit, and vocational vehicles equipped with Cummins ECO‑FIT ISB 6.7L / B6.7 engines. Especially useful where DEF system performance and emissions compliance are critical for daily operations.

Installation Notes
Install by a qualified technician. Depressurize or isolate the DEF tank before beginning. Inspect sealing surfaces and replace any damaged O‑rings or gaskets. Mount the unit to OEM torque specifications. After installation, verify proper sensor readings, check for leaks, and clear any faults via diagnostic tools. 

Final Thoughts
If your ISB 6.7L or B6.7 ECO‑FIT engine is having DEF warning lights, inconsistent readings, or you’re replacing emission components, the OEM 5511561 DEF Head Unit offers a reliable replacement. With factory fit, accurate sensor readings, and robust construction, it restores emission control integrity and supports long‑term vehicle reliability.