When your modern Paccar PX9 truck (model years 2022-2024) is humming down the highway, one of the unseen parts doing constant work is the DEF (Diesel Exhaust Fluid) sensor. The OEM M31-6026 DEF sensor / heater assembly is a critical component that helps your engine management system “see” the state of your DEF fluid—temperature, quality, and readiness for injection. Get this sensor wrong, and your SCR system may flag errors, refuse regeneration, or even derate the engine.
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Monitors DEF fluid temperature to prevent freeze or crystallization under cold conditions
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Detects fluid quality / urea concentration so the engine knows whether the fluid is usable
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Provides data feedback to regulate precise dosing of DEF into the exhaust stream
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Helps avoid fault codes, system warnings, or engine derates tied to bad sensor readings
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Comes with built-in heating elements (heater assembly) to keep the sensor active in colder environments
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Engineered to OEM tolerances for plug-and-play compatibility with PX9’s DEF system
Your DEF system is only as good as the sensor that guides it. The OEM M31-6026 DEF Sensor / Heater Assembly ensures your emissions control stays responsive, reliable, and compliant—even in temperature extremes. Don’t let a failing or mis-matched sensor become your emissions weak point—install quality, test accuracy, and keep your PX9 running clean.
