DEF Level Sensors

DEF level sensors monitor the amount of diesel exhaust fluid in the DEF tank and communicate this information to the vehicle’s emissions control system. At Advanced Truck Parts, we supply DEF level sensors for Cummins, Detroit Diesel, Paccar, Volvo, Mack, and other heavy-duty diesel truck platforms with fitment verification before purchase.

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What a DEF Level Sensor Does

A DEF level sensor measures the amount of diesel exhaust fluid inside the DEF tank and sends this information to the truck’s emissions control system. The sensor helps ensure the vehicle maintains proper DEF levels so the SCR system can operate correctly and reduce emissions.

How DEF Sensors Work with the Emissions System

The DEF level sensor communicates with the aftertreatment control module (ACM) and engine control module (ECM). These systems monitor DEF levels, fluid quality, and temperature to maintain proper SCR system operation and emissions compliance.

Common Engines Using DEF Systems

DEF systems are used across many modern heavy-duty diesel engine platforms including:

Cummins ISX, X15 and ISB 6.7 engines
Detroit Diesel DD13, DD15 and DD16 engines
Paccar MX-13 and MX-11 engines
Volvo D11, D13 and D16 engines
Mack MP7, MP8 and MP10 engines
International A26 and MaxxForce engines
Hino J08 and A09 engines

Common Signs of DEF Level Sensor Failure

Incorrect DEF level readings
DEF system warning lights
SCR or emissions fault codes
Engine derate conditions
DEF gauge stuck at empty or full

When a DEF sensor fails, the emissions system may not receive accurate fluid level data, which can trigger warning lights and may eventually lead to engine derate conditions.