When you’re operating equipment or trucks with CAT C4.4 or C3.6 engines, each link in the emissions aftertreatment system has to work flawlessly. One of the most important—but overlooked—components is the DEF (Diesel Exhaust Fluid) head unit. The correct DEF head ensures accurate sensing, precise dosing, and reliable communication between your DEF system and the engine control module. If it malfunctions or drifts out of spec, you’re looking at error codes, derates, or regulatory compliance risks.
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Monitors DEF fluid level, temperature, and urea concentration, providing real-time data to your ECU
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Regulates accurate dosing of DEF into the exhaust stream, enabling the SCR (Selective Catalytic Reduction) system to properly reduce NOx emissions
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Built to match CAT’s OEM specifications for the C4.4 and C3.6 platforms for proper fit and calibration
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Helps prevent emissions fault codes, warning lamps, or engine derates resulting from sensor errors
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Designed to withstand harsh conditions—vibration, temperature swings, and exposure to DEF’s corrosive nature
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Engineered for efficient replacement, allowing for quicker repairs and less downtime
Don’t let a compromised DEF head unit become the weak link in your emissions system. By installing an OEM-matched DEF Head for your CAT C4.4 or C3.6 engine, you restore system accuracy, protect against unexpected faults, and keep your machine running clean and compliant. This is one of those parts that might be small in size—but is huge in importance.