Dorman 904-375 Diesel Exhaust Fluid (DEF) Heater

Dorman 904-375 DEF Heater for Mercedes-Benz Diesel Applications

The Dorman 904-375 Diesel Exhaust Fluid (DEF) Heater is an OE FIX replacement for vehicles where the factory DEF heater can fail from fluid intrusion. It updates the original design to address that common failure point and improve long-term reliability. Compatible With select Mercedes-Benz ML350, ML400, and ML320 diesel applications.

Key Features

• OE FIX design addresses a known fluid-intrusion failure point in the factory DEF heater
• Specific fit for select Mercedes-Benz diesel models
• Plastic housing with black finish
• Female inlet and outlet fittings
• 7-terminal electrical connector with 2 electrical connectors
• Level sensor type: resistor
• Mounting hardware included
• Part number: 904-375

Detailed Description

This Dorman DEF heater is built for direct replacement on select Mercedes-Benz diesel vehicles and follows the original equipment layout while revising the weak point that can allow fluid intrusion. The housing is plastic, the unit uses female inlet and outlet fittings, and the electrical interface includes two connectors with seven terminals. The 904-375 application coverage includes 2007-2009 Mercedes-Benz ML320, 2010-2011 Mercedes-Benz ML350, and 2015 Mercedes-Benz ML350 and ML400 diesel models. If you are searching for a Mercedes-Benz ML350 DEF heater replacement or a Mercedes-Benz ML320 DEF heater with OE-style fitment, this part number is a direct match for the listed applications.

This part cross-references Mercedes-Benz 1644711175 for the same application.

Common Problems This Part Addresses

• DEF heater failure caused by fluid intrusion
• Loss of DEF heating performance in cold conditions
• Warning lights related to DEF system faults
• Incorrect DEF tank temperature control
• Need for a direct-fit replacement on listed Mercedes-Benz diesel models

Installation Notes and Tips

Verify the vehicle’s year, model, and body code before ordering. This part is a specific-fit component and should be matched to the listed Mercedes-Benz ML320, ML350, or ML400 applications. Inspect the DEF tank and electrical connectors for corrosion or damage before installation, and confirm the connector style and fitting orientation match the original unit. The included mounting hardware supports installation, but the vehicle should be checked for any related DEF system faults after replacement.

Quality Assurance

Dorman OE FIX components modify the original design to correct known failure points while maintaining application-specific fitment. Part number 904-375 is engineered for the listed Mercedes-Benz diesel applications and follows the OE-style configuration needed for proper DEF system service.