In modern diesel systems, the DEF (Diesel Exhaust Fluid) circuit is much more than a tank and a pump — it’s an active feedback loop. For TEMSA vehicles powered by Cummins engines, the DEF Head Unit (OEM RP169181, Tamerx part 4310-11-28) serves as the brain of that loop. When functioning correctly, it monitors fluid properties and ensures clean, accurate dosing. When it falters, your SCR system, diagnostics, or engine behavior can suffer.
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Monitors DEF fluid level, temperature, and urea concentration, supplying precise data back to the vehicle’s ECU
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Regulates correct dosing of DEF into the exhaust stream so the SCR (Selective Catalytic Reduction) system can perform NOx conversion
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Designed to match the OEM RP169181 spec for TEMSA/Cummins compatibility and calibration integrity
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Helps prevent error codes, system warnings, or engine derates often caused by sensor drift or faulty feedback
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Includes a 40-micron filter to protect against contaminants entering the DEF plumbing
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Engineered to withstand real operating conditions: vibration, thermal cycles, and exposure to DEF chemistry
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Backed by a 1,000,000-mile or 1-year warranty when installed properly
Running with a failing or out-of-spec DEF head unit is a risk — one that can lead to reduced reliability or unwanted maintenance stops. By installing the correct OEM RP169181 TEMSA / Cummins DEF Head Unit, you restore accuracy to your emissions system, safeguard SCR function, and reduce the chance of surprise faults. In the emissions chain, this small module carries significant responsibility.
























































