Driving a Cummins ECO-FIT (ISB 6.7L / B6.7) engine means your aftertreatment system is under constant scrutiny. At the heart of that system is the DEF (Diesel Exhaust Fluid) head unit. The ECO-FIT DEF Head Unit, built to OEM 5511561 specifications, provides critical sensing, dosing, and feedback functions. When it fails or drifts from spec, you risk emissions faults, warning lights, or even engine derates.
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Measures DEF fluid level, temperature, and urea concentration, sending that data to the engine control module
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Controls precise dosing of DEF into the exhaust stream to support the SCR (Selective Catalytic Reduction) system’s NOx reduction
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Designed to meet OEM 5511561 tolerances for seamless compatibility with the ECO-FIT / ISB 6.7L / B6.7 application
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Helps prevent fault codes, emissions warnings, and engine derates triggered by incorrect sensor readings
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Built to withstand vibration, thermal cycling, and exposure to corrosive DEF chemistry
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Simplified replacement design helps reduce vehicle downtime
Many failures in emission systems trace back to a degraded DEF head whose readings no longer reflect reality. Installing the correct OEM 5511561 ECO-FIT DEF Head Unit restores your system’s accuracy, safeguards you from unexpected derates, and ensures your emissions system remains reliable. Don’t let a small component become your biggest liability.