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.

Verify Fitment Before Ordering

DEF sensors are emissions-system specific and may vary by engine platform and tank configuration. To confirm compatibility quickly provide:

• Engine serial number
• Current DEF sensor part number
• Truck VIN number
• Year / Make / Model of truck
• Photos of the DEF tank sensor if available

Why Buy DEF Level Sensors from Advanced Truck Parts?

• Fitment verification before purchase
• Competitive pricing on heavy-duty diesel parts
• Fast nationwide shipping
• Business account discounts available
• Trusted U.S.-based commercial truck parts supplier