In fire trucks and emergency vehicles, downtime is not an option—and emissions compliance is a must. The Eldorado Cummins DEF Head Unit, built to OEM 840175 specs (Tamerx part 5410-22-FC01-4), acts as the pivotal control unit in your DEF (Diesel Exhaust Fluid) circuit. A failing DEF head can quickly escalate from a nuisance fault to derated engine operation when you least expect it.
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Monitors fluid temperature, level, and urea concentration and relays real-time data to the ECU
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Enables precise dosing of DEF into the exhaust stream, supporting the SCR (Selective Catalytic Reduction) system’s NOx conversion
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Designed for drop-in compatibility with Eldorado / Cummins platforms thanks to OEM 840175 engineering
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Reduces risk of fault codes, emissions warnings, and derate events due to inaccurate sensor signals
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Built to withstand harsh environments: vibration, thermal cycling, and DEF’s corrosive nature
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Replacing it restores system integrity and helps your vehicle maintain regulatory compliance
Emergency vehicle operators can’t afford surprises—especially ones tied to emissions systems. Installing the OEM 840175 Eldorado Cummins DEF Head Unit ensures your DEF circuit remains accurate, reliable, and ready for mission-critical duty. Keep your rig compliant and ready, so you’re never sidelined when you can’t afford to be.






















































