Diesel exhaust fluid is quite important for modern diesel engines. Many drivers hear the term and still feel unsure about what DEF is made of and why diesel engines need it.
DEF is made of urea and deionized water. This simple DEF composition raises questions about safety, quality, and engine impact. Modern diesel engines have SCR systems that need diesel exhaust fluid for proper functioning. Missing even one refill can turn on warning lights, reduce engine power, and stop equipment.
As per the EPA, the vehicles using DEF must meet emissions rules, which can be achieved through advanced exhaust aftertreatment design. SCR systems reduce nitrogen oxide emissions in diesel engines. Sensors monitor DEF levels, and low supply or poor quality can cause fault codes, limit engine power, and shut down equipment.
Therefore, fleet vehicles, generators, and heavy equipment require diesel exhaust fluid to operate effectively. DEF issues can cause schedule delays, increase costs, and affect compliance. This blog explains what does DEF contain, how it works in modern diesel engines, and why using it is essential.
You will learn how SCR systems use DEF and how to avoid system faults. Rhino Fuel supplies DEF at your business address, so you don’t face shortages.
Key Takeaways
- DEF is made of 32.5% high-purity urea and 67.5% deionized water. Any change can harm the SCR system.
- Diesel engines with SCR systems cannot operate without DEF and may enter limp mode or shut down if DEF runs out or is contaminated.
- DEF is not fuel and never enters the engine. It works in the exhaust to reduce harmful NOx emissions.
- Quality matters. DEF must meet ISO 22241 standards to avoid sensor failure, catalyst damage, and costly repairs.
- Do not make your own DEF because low-quality or DIY DEF can contaminate the system and cause engine failure.
- A reliable DEF supply is important for fleets, job sites, and generators to prevent downtime and compliance issues.
What Diesel Exhaust Fluid Is Made Of
Diesel exhaust fluid is a mix of 32.5% high-purity urea and 67.5% deionized water. Small changes in the urea and water mix can cause sensor failures, lower system performance, and damage the catalyst.
Besides this, the purity of DEF also matters. DEF must meet strict standards to prevent contaminants from reaching the exhaust system. Impurities can block injectors, activate warning codes, or lead to expensive repairs. That is why only certified DEF should be used in vehicles and equipment.
Diesel exhaust fluid composition is different from that of fuel and engine additives. It never goes into the engine itself. Instead, it acts in the exhaust stream to react with gases and lower pollution. DEF and the SCR system work together to reduce harmful nitrogen oxide emissions in diesel engines.
Why Diesel Engines Require DEF to Operate
Why diesel engines need DEF becomes clear when you look at emissions. Diesel engines release nitrogen oxides that harm air quality and human health. DEF works inside the selective catalytic reduction system to lower these emissions.
You must know how diesel exhaust fluid works to understand its role in diesel engines. Stricter emission rules required manufacturers to adopt SCR systems.
Modern diesel engines are built around DEF use. They have sensors that check fluid levels and quality. Engines may reduce power or shut down if DEF is low or contaminated. They do so to protect engine performance and the exhaust system.
What Happens When DEF Runs Low or Runs Out
Diesel vehicles monitor DEF levels and display a warning on the dashboard when the fluid is low. Ignoring these alerts can cause major engine restrictions. Vehicles may lose acceleration and have trouble carrying heavy loads.
Low DEF activates engine derate and limp mode. In this state, the engine reduces power to control emissions. Engines may not start at all if DEF runs out completely. SCR systems cannot operate without DEF, and the system blocks engine operation to prevent damage.
This is why you must understand everything related to DEF and its role in your diesel engine. Knowing what happens if DEF runs out helps you act quickly and prevent sudden shutdowns.
Why DEF Quality and Certification Matter
The DEF ISO 22241 standard sets the rules for the quality, handling, storage, and refilling of diesel exhaust fluid. It defines how the urea solution used in SCR systems should be made, stored, tested, and delivered so engines and emission systems work correctly.
Always use DEF that meets the ISO 22241 standard to follow emission rules. Improper handling, such as exposure to dirt, water, or the wrong container, can also cause various problems. Contaminated or low-quality DEF can damage SCR systems, block sensors, and reduce engine power.
Can Diesel Engines Run Without DEF
You might have this question in mind: “Can a diesel engine run without DEF?”
Modern diesel engines with SCR systems need DEF to meet emissions standards. Skipping or bypassing DEF is illegal and harmful. It violates EPA regulations and also causes serious mechanical problems.
Disabling or deleting DEF systems activates automatic engine responses. Sensors detect the missing or poor-quality fluid. These protections prevent excess nitrogen oxide emissions and enforce compliance with legal requirements.
Long-term damage is another major risk. The SCR system requires accurate DEF injection, and using low-quality or no DEF can clog injectors, damage catalysts, and fail sensors. Rhino Fuel offers emergency DEF delivery services. We also supply DEF at our customers’ business locations during urgent situations.
Why You Should Never Make Your Own DEF
Some operators make their own diesel exhaust fluid at home to save money. Such tactics might seem fine, but in reality, they are risky. One must know the exact DEF ingredients to make sure the diesel exhaust fluid performs effectively in the engine’s SCR system.
Using anything less than industrial-grade urea can be problematic for a diesel engine. Authorized industries prepare the best quality urea through controlled chemical processes. It is free from impurities and meets ISO 22241 standards.
Household or agricultural urea is not pure enough. These forms contain minerals and contaminants that can damage the SCR system in diesel engines. Contaminants clog sensors and reduce their accuracy. So, you must always use certified DEF to protect sensors and catalysts.
You can contact Rhino Fuel for on-site delivery of fuel and DEF to save time and money.
Proper DEF Storage and Handling for Fleets and Job Sites
Using selective catalytic reduction DEF requires careful storage to protect its effectiveness. Temperature and contamination can degrade diesel exhaust fluid. It breaks down in heat and freezes in cold. Dirt, oil, or other fluids can damage the SCR system if they mix with DEF.
Apart from this, the shelf life of DEF also matters. DEF starts degrading over time due to sunlight and air exposure. DEF can also freeze in cold weather, so it needs proper handling during thawing.
You must rotate stock and check expiration dates to keep the fluid reliable for diesel engines. Manage the fuel storage and dispensing carefully, especially when you buy in bulk from a delivery agency.
Make sure to use clean tanks for DEF storage and keep them separate in shaded or climate-controlled areas. You must also keep the DEF dispensing tools away from contaminants.
Ensuring Reliable DEF Supply for Continuous Operations
Emission systems respond immediately to low levels or contaminated fluid. Power output of vehicles and equipment reduces even if there are no mechanical issues in the engine. These interruptions usually happen due to missed refills and weak supply planning.
Sellers may offer low-quality diesel exhaust fluid. This is why you must be careful while purchasing DEF. Correct DEF quality protects SCR components from damage. Find a trustworthy fuel delivery supplier who can offer the recommended DEF quality.
You can also schedule DEF delivery to reduce supply issues and avoid downtime. Plan mobile fuel and DEF refills based on actual consumption at fleets and job sites. Supplier quality affects compliance and uptime. Order fuel from Rhino Fuel and get the benefit of on-site refueling.
Frequently Asked Questions
what is def made of
What is the main ingredient in DEF?
Urea is the main ingredient in diesel exhaust fluid. It is mixed with a specific volume of deionized water to create diesel exhaust fluid.
What kind of urea is DEF made from?
DEF is made from high-purity urea, specifically designed for diesel exhaust systems. It is different from agricultural or industrial urea, which can contain impurities.
Where do they get urea for DEF?
Urea for DEF is produced in the chemical industry using ammonia and carbon dioxide. It is refined to high purity before use in diesel exhaust fluid.
Can I make my own DEF fluid?
You should not make your own DEF. Homemade DEF can be contaminated and damage the SCR system. This is why you must use commercially prepared DEF that complies with ISO 22241 standards.
Get DEF and Fuel Delivered Fast with Rhino Fuel
Rhino Fuel is a reputed fuel delivery agency that supplies fuel to fleet companies and various other job sites. We provide all types of fuel, including diesel, petrol, and high-quality diesel exhaust fluid.
Our products meet industry standards. This way, your diesel engines and emissions systems remain safe and compliant. Rhino fuel also allows you to schedule regular on-site deliveries.
