Diesel Exhaust Fluid (DEF) Information

Diesel Exhaust Fluid (DEF) is an essential non-toxic solution comprised of urea and deionized water, specifically formulated to help modern Sprinter vans comply with stringent emissions standards. This fluid plays a critical role in reducing harmful nitrogen oxide (NOx) emissions produced during the combustion process by converting them into harmless nitrogen and water within the Selective Catalytic Reduction (SCR) system.

When the DEF tank reaches a low level, a warning indicator will illuminate on the dashboard, signaling that it's time to replenish the fluid. If the DEF is not refilled in a timely manner, the vehicle may enter a protective limp mode, limiting performance, or may even prevent starting altogether to safeguard the engine.

To refill the DEF tank, begin by locating the distinct blue "DEF only" cap situated conveniently under the hood. Use a dedicated dispensing nozzle or funnel designed for DEF to ensure a clean and efficient refill process. Once filled, make sure to securely fasten the cap to maintain the integrity of the system and prevent contamination. Regularly checking and maintaining the DEF level is crucial for optimal vehicle performance and compliance with emissions regulations.


What is DEF?

Composition: A 32.5% urea and 67.5% water solution.

Purpose: To break down nitrogen oxides (NOx) into water and nitrogen in the SCR system.

Safety: It's a stable, colorless, odorless, and non-toxic solution but corrosive to copper, so avoid contact with copper cables.

How to Add DEF

Locate the Fill Point: Open the hood to find the blue "DEF only" cap.

Use a Dedicated Nozzle: The container's nozzle or a provided funnel will fit this specific port.

Fill the Tank: Pour the DEF into the reservoir until the tank is full.

Secure the Cap: Replace the cap and ensure it's tightly secured.


Why Your Sprinter Needs It

Emissions Control: DEF is essential for meeting modern emissions standards by treating exhaust fumes.

System Malfunction: A DEF warning light indicates a low level, contamination, or a fault with the system.

Important Considerations

Don't Ignore Warnings: The system will eventually prevent the engine from starting if the DEF tank is empty.

Use Pure DEF: Only use high-quality DEF that meets ISO standards (ISO 22241).

Avoid Contamination: Do not mix DEF with fuel, coolant, or engine oil.

Storage: If your van is stored for an extended period, the DEF quality may degrade, so it's advisable to use a fresh, high-quality supply

  1. Knauz Continental Autos

    409 Skokie Valley Hwy.
    Lake Bluff, IL 60044

    • Sales: (847) 235-3800
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Get in Touch

409 Skokie Valley Hwy.
Directions Lake Bluff, IL 60044

  • Contact our Service Department at: 847-235-3800

Service Department Hours

  • Monday - Friday7:00AM - 5:00PM
  • SaturdayClosed