Dorman 904-378 Diesel Exhaust Fluid (DEF) Heater

Reliable Diesel Exhaust Fluid Heater for Volkswagen Passat

The Dorman 904-378 Diesel Exhaust Fluid (DEF) Heater is designed specifically for Volkswagen Passat models to ensure optimal DEF system performance in cold conditions. This DEF heater helps maintain fluid temperature, preventing crystallization and ensuring proper emission control.

• Inside diameter of 115 mm for precise fitment
• Includes two electrical connectors with male and female terminals
• Mounting hardware included for straightforward installation
• Durable black plastic housing measuring 150 mm in height
• Female inlet and outlet fittings for secure hose connections
• Resistor-type level sensor integrated
• Multiple wire colors (black, white, yellow, blue, red, gray) with plastic insulation

Product Details and Specifications

The Dorman 904-378 DEF Heater is engineered with a plastic housing that offers durability while maintaining a lightweight design. Its specific fitment for Volkswagen Passat models ensures compatibility and reliable operation within the vehicle’s emission control system. The heater features two electrical connectors with both male and female terminals, supporting three to four terminal connections, which facilitates seamless integration with the vehicle’s wiring harness. The heater’s inlet and outlet fittings are female type, designed to connect securely with the DEF system hoses (hose not included). The resistor-type level sensor helps monitor fluid levels accurately, contributing to efficient system management.

Purpose and Common Applications

• Prevents DEF crystallization in cold weather conditions
• Maintains proper DEF fluid temperature for emission compliance
• Supports reliable operation of the vehicle’s selective catalytic reduction (SCR) system
• Helps avoid DEF system faults and warning lights
• Ensures consistent engine performance and reduced emissions

Installation Notes and Tips

Installation of the Dorman 904-378 DEF Heater is straightforward with included mounting hardware. Ensure the heater is installed in the correct orientation with female inlet and outlet fittings properly connected to the DEF lines. Verify electrical connectors match the vehicle’s wiring harness terminals (male and female) and confirm secure connections to prevent electrical issues. It is recommended to inspect the DEF lines and connectors for damage during installation and replace any worn components to maintain system integrity.

Quality Assurance and Warranty

Dorman parts are manufactured to meet or exceed OEM standards, providing reliable performance for emission control components. The 904-378 DEF Heater undergoes rigorous quality checks to ensure durability and functionality. While specific warranty details may vary, Dorman typically offers a limited warranty covering defects in material and workmanship, supporting confidence in the product’s longevity and fitment for Volkswagen Passat vehicles.