In diesel engine aftertreatment systems, the DEF (Diesel Exhaust Fluid) head unit often flies under the radar—until things break down. On CAT’s C4.4 engines, it’s a vital part of the emissions chain, delivering feedback that the engine’s control module relies on to keep everything running clean and compliant. The CAT C4.4 DEF Head Unit (OEM 5913427) is engineered to take on that role without hesitation.
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Monitors DEF fluid level, temperature, and quality (urea concentration) through built-in sensors
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Relays that data via CAN bus or appropriate signal lines to the engine’s control module
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Ensures the correct dosing of DEF into the exhaust stream so the SCR (Selective Catalytic Reduction) system can reduce NOx properly
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Helps prevent error codes, emissions warnings, or derates that often start with a defective DEF head
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Built to survive tough conditions: vibration, thermal cycling, and exposure to DEF chemistry
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Packaged and calibrated to OEM specs, making it easier to install without extensive tuning
When your emissions system starts acting up—with warning lights or system faults—most problems trace back to sensing faults first. The OEM 5913427 DEF Head for the CAT C4.4 restores proper feedback, stabilizes emissions operation, and gives you confidence that your aftertreatment system can do its job without surprises. In short: don’t wait for that warning light—make sure this sensor is in strong shape.
