Can DEF Freeze?
With winter in full swing throughout North Carolina, Virginia, Tennessee and West Virginia, fleet managers know that they’ll be dealing with more than cold mornings and icy roads. The frigid temperatures affect how diesel fleets operate, especially when it comes to Diesel Exhaust Fluid, or DEF.
This essential fluid keeps trucks fully compliant with emissions standards, but as the weather gets colder, many fleet owners ask the same question: Can it freeze, and what happens if it does?
What Is DEF & Why It Matters
DEF is a critical part of every modern diesel engine. Made from 32.5% high-purity urea and 67.5% deionized water, it works within your truck’s Selective Catalytic Reduction (SCR) system to break down harmful nitrogen oxide (NOx) emissions into harmless nitrogen and water vapor. The result is cleaner air, better efficiency and compliance with today’s environmental standards.
Does It Freeze?
Yes, it does freeze at 12°F (-11°C), a temperature that’s not uncommon during winter across the Mid-Atlantic.
The good news? Freezing won’t harm your DEF.
Once it thaws, it returns to its original concentration and performance. Most diesel trucks are now equipped with built-in tank heaters. These heaters automatically warm the fluid as the engine runs, ensuring it flows properly and your emissions system continues to work as designed.
How to Properly Handle DEF in Cold Weather
Even though DEF can freeze, fleet managers have several strategies to keep it flowing smoothly:
- Store it indoors or in heated garages whenever possible
- Regularly check its levels, as a lower urea concentration can increase the risk of freezing
- Make sure a truck’s DEF tank heater is functioning properly
- Avoid using anti-gel or antifreeze additives in holding tanks
- Rotate your stock so that the older fluid is used first
- Allow the vehicle engine to warm up before driving if parked in cold conditions
Partner With a Distributor You Can Trust
Even in the coldest months, DEF freezing isn’t a cause for alarm. Proper care and quality fluids ensure your fleet stays on the road and emissions-compliant. Reach out today, so we can help keep your fleet compliant no matter how cold the weather gets.
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