Dorman 904-377 Diesel Exhaust Fluid (DEF) Heater

Reliable Diesel Exhaust Fluid Heater for Mercedes-Benz GL320 and GL350

The Dorman 904-377 Diesel Exhaust Fluid (DEF) Heater is designed specifically for Mercedes-Benz GL320 and GL350 models. This DEF heater ensures optimal performance of your vehicle's emission control system by maintaining the proper temperature of the diesel exhaust fluid in cold conditions.

• Compatible with Mercedes-Benz GL320 and GL350
• Specific fit for precise installation
• Durable black plastic housing measuring 206 mm in height
• Includes mounting hardware for straightforward installation
• Equipped with male and female electrical connectors with 3 and 4 terminal configurations
• Features resistor-type level sensor for accurate fluid monitoring
• Inlet and outlet fittings are female type for secure hose connections
• Wire insulation made of plastic with multiple wire colors for easy identification

Product Details and Specifications

The Dorman 904-377 DEF heater is engineered with a 115 mm inside diameter housing constructed from durable black plastic. It includes two electrical connectors with male and female terminals, supporting both 3 and 4 terminal configurations to ensure compatibility with the vehicle’s wiring harness. The heater comes with all necessary mounting hardware, simplifying the replacement process. The inlet and outlet fittings are female type, designed to connect securely with the vehicle’s DEF system hoses (hose not included). The resistor-type level sensor integrated into the unit provides reliable fluid level detection, helping maintain proper DEF system operation. Wire insulation is plastic, and the wiring includes black, white, yellow, blue, red, and gray colors for easy identification during installation.

Purpose and Common Issues Addressed

• Prevents diesel exhaust fluid from freezing in cold weather
• Maintains proper DEF temperature for effective emission control
• Ensures accurate DEF level sensing to avoid system errors
• Helps reduce emission-related warning lights and faults
• Supports compliance with emission regulations by maintaining DEF system functionality

Installation Notes and Tips

Installation of the Dorman 904-377 DEF heater requires compatibility with Mercedes-Benz GL320 and GL350 models. Ensure the vehicle is powered off before beginning installation. Use the included mounting hardware to secure the heater in place. Verify that the male and female electrical connectors are properly matched and securely connected. Since the heater does not include hoses, inspect existing DEF hoses for wear or damage and replace if necessary. Properly route and secure wiring to prevent abrasion or disconnection during vehicle operation.

Quality Assurance and Warranty

Dorman parts are manufactured to meet or exceed OEM standards for fit, form, and function. The 904-377 DEF heater undergoes rigorous quality control to ensure reliable operation within the emission control system. This part is backed by Dorman’s limited warranty, providing coverage against defects in material and workmanship under normal use conditions.