Running modern trucks or equipment with selective catalytic reduction (SCR) systems means the Diesel Exhaust Fluid (DEF) head unit isn’t optional—it’s essential. The Tenneco DEF Head Unit (OEM 82249729, part number 1731-13-3) plays a key role in making sure your emissions control system works properly. Without it, misread sensors, error codes, or even system derates can put you off the road when you least expect it.
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Monitors DEF fluid level, temperature, and quality (urea concentration) to send accurate data to the engine control module
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Controls correct dosing of DEF into the exhaust stream so the SCR system can reduce NOx emissions as designed
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Built to OEM 82249729 specifications, ensuring a plug-and-play replacement with correct calibration
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Includes features like a 40-micron filter and coaxial heater to protect against contamination and freezing or crystallization in cold weather
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Helps prevent warning lights, system fault codes, or engine derates resulting from sensor drift or degraded units
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Designed to withstand harsh operating conditions: vibration, temperature swings, and exposure to DEF fluid’s corrosive nature
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Comes with a solid warranty (1 million miles or 1 year), giving peace of mind with the replacement
When emission faults or derates appear, the DEF head unit (OEM 82249729) is often one of the first components to check. Replacing it with a high-quality unit restores accuracy to your emissions system, prevents unexpected downtime, and helps ensure compliance with emissions regulations. Don’t let this small but crucial component be your weak link.