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Does DEF Go Bad? Dealing With DEF Issues

Does DEF Go Bad? Dealing With DEF Issues

Does DEF Go Bad? Dealing With DEF Issues

Does DEF Go Bad? Dealing With DEF Issues

Reading time: 5 min

Recently, there has been a lot of chatter about DEF. Since 2010, the EPA has required diesel engines to reduce their production of nitrogen oxides, which adversely impact the environment.

In heavy equipment, nitrogen oxide (NOx) emissions are reduced using a liquid, called diesel exhaust fluid (DEF), which converts nitrogen oxide in the machine’s exhaust stream into harmless water and nitrogen. 

This process, called selective catalytic reduction (SCR), is a key feature of modern heavy equipment exhaust systems. As a result, most modern machines will not run without DEF.

Understanding the significance of DEF and how to properly store and maintain it is vital for fleet managers and heavy equipment operators.

In this article, we’ll dive into the question of whether DEF can go bad, and explore the impacts of DEF on the optimal functioning of heavy machinery.

Does DEF Go Bad?

One common concern among heavy equipment operators and fleet managers is whether DEF can go bad over time. The good news is that, when stored and handled correctly, DEF has a long shelf life.

Under normal circumstances, DEF can last up to one year when stored at normal temperatures (between 23°F and 68°F). However, several factors can impact its longevity and effectiveness.

One of the main reasons DEF might go bad before the expected expiration date is contamination. DEF is highly sensitive to impurities, such as dust, dirt and other substances that can compromise its chemical composition.

Contamination can occur during storage or handling, making it essential to follow proper storage and dispensing practices.

Another factor that can affect the quality of DEF and shorten its storage life is sunlight. Direct exposure to sunlight can degrade the fluid and cause it to break down prematurely. To mitigate this risk, DEF should be stored in opaque containers or in a shaded area to shield it from sunlight.

Cold temperatures can also impact DEF. When subjected to freezing temperatures, DEF can crystallize and expand, corrupting the fluid and rendering it unusable.

Additionally, if DEF is exposed to air for an extended period or stored in containers with significant headspace, it can lead to water evaporation and crystallization. To prevent crystallization, it’s crucial to ensure proper sealing and avoid leaving DEF containers partially empty.

How to Tell if DEF Is Bad

Detecting potential issues with DEF is crucial for maintaining the optimal performance of heavy equipment. Understanding the symptoms of bad DEF can help operators and fleet managers address problems promptly and prevent potential failures. For starters, the DEF used in an SCR system must be exceedingly pure. DEF can become contaminated easily, and contaminated DEF can cause problems with your machine’s exhaust system.

Some common issues associated with contaminated DEF include:

  • An uptick in DEF consumption
  • Excess smoke or dark exhaust
  • Engine failure

In addition to DEF contamination, another common issue associated with heavy equipment exhaust systems is DEF pump failure.

In a machine’s SCR system, DEF is pumped into the SCR chamber where it is allowed to react with the engine exhaust before being expelled through the system via the exhaust pipe.

When the DEF pump fails, DEF cannot be pumped from the DEF tank into the catalyst, resulting in contaminated exhaust being expelled from the system.

Some signs of a failing DEF pump include engine warning lights, exhaust system warning lights/codes and highly polluted exhaust.

How to Store DEF

Proper storage of DEF is essential to maintain its integrity and effectiveness. By following recommended storage practices, heavy equipment operators can ensure that DEF remains in optimal condition for usage.

DEF Storage Temperature

First and foremost, DEF should be stored in a cool and dry location. The storage area should be kept between 23°F and 68°F. This temperature range helps preserve the quality and longevity of the DEF.

When it comes to choosing a container for DEF storage, it is critical to use a container made from a suitable material. High density polyethylene plastic containers or dedicated DEF tanks are commonly used and recommended for storing DEF.

Importantly, DEF containers should not have too much headspace, so it’s a good idea to fill them to capacity. Too much empty room in the containers can cause excessive condensation of the DEF, which may lead to crystallization.

When stored according to best practices, the shelf life of DEF is around one year. However, you should always check the expiration date mentioned on the container to ensure freshness and avoid using DEF that is too old.

DEF Common Questions

What does it mean for DEF to be API certified?

DEF that is API certified (American Petroleum Institute) meets the quality and standards set forth by the API. To meet this standard, DEF needs to have a particular composition, level of purity and quality. DEF that meets this standard typically has the API certification mark displayed on its packaging. 

Safety Concerns When Handling DEF

DEF is generally non-toxic and poses minimal safety concerns. While DEF is non-hazardous, it should never be mixed with other fluids or contaminants. Also, when handling DEF, it is advisable to wear protective gloves and glasses, as taking these precautions can prevent irritation and discomfort.

What’s the difference between DEF and fuel?

While fuel is combusted in the machine’s engine, DEF is part of the machine’s exhaust system. DEF is stored in a dedicated tank on the machine, and is not mixed with fuel. Instead, DEF is atomized and injected in a machine’s SCR chamber, where it interacts with the engine’s exhaust and converts nitrogen oxides into harmless nitrogen and water.

What happens when a machine runs out of DEF or has low DEF?

In modern machines, engines are commonly equipped with control systems that monitor DEF levels. When DEF drops below a certain level or runs out, the machine’s engine control module may activate a reduced power mode which limits the engine’s performance. The DEF tank should be topped off frequently to avoid running out of DEF and to minimize condensation inside the DEF tank.

What Happens if You Use Expired DEF?

Using contaminated or expired DEF can have several consequences that may affect both the DEF system and other components of your machine. Some common problems include reduced performance, increased emissions, damage to the DEF system and possibly engine malfunction.

How Do You Properly Dispose of DEF?

Although DEF is not toxic, it must be disposed of properly. Excess, expired or contaminated DEF can typically be brought to a hazardous waste recycling center. Before disposing of DEF, be sure to check your state regulations and take the necessary steps to adhere to local environmental regulations.

Final Thoughts

DEF plays a crucial role in heavy equipment, aiding in emission reduction and environmental compliance. By properly storing DEF, monitoring its levels in your machine, avoiding contamination and adhering to manufacturer recommendations, operators can ensure optimal performance and emissions compliance.

By staying informed and paying special attention to a machine’s DEF usage, heavy equipment operators can contribute to a cleaner environment while maintaining the reliability and productivity of their fleet. 

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