Emission levels and pollution have almost entirely defined the current
automobile landscape. And, since the passage of the Clean Air Act in 1975, cleaner-burning engines have been the top priority. Manufacturers have tried a wide range of technologies to reduce tailpipe emissions, most notably the ever-critical catalytic converter, which we previously discussed. However, diesel vehicles use a special, almost phony-sounding liquid to help them burn cleanly: diesel exhaust fluid.
Diesel exhaust fluid (DEF) is a real thing. But what exactly does it do? What is the process of cleaning toxic fumes?
Much every contemporary diesel engine, particularly those built after Dieselgate, has a selective catalytic reduction (SCR) system that injects DEF into the exhaust. It's a critical piece of emissions equipment that most states frown upon removing. Although it is a highly specialized piece of equipment, there are several excellent reasons why modern diesel engines use SCR and DEF to keep healthy.
Diesel fumes fluid purifies the air.
Diesel engines are unclean, and the myth of "clean diesel" was disintegrated when Volkswagen's emissions dishonesty was revealed in 2015. The increased scrutiny prompted research into the true environmental cost of diesel engines, which revealed that even if diesel engines were
relatively clean of carbon dioxide (CO2), significant soot and NOx emissions would still occur.
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Types of diesel can be manufactured fairly safely, but staying clean necessitates a much more sophisticated system.
DEF is injected into the exhaust of a diesel engine at a strategic point to reduce certain harmful pollutants, much like a chemical catalytic converter. It does not react with all of the combustion byproducts in the exhaust, but it does react with the most dangerous emissions from diesel engines: oxides of nitrogen, or NOx.
DEF contains 32.5% urea and 67.5% deionized water. Urea is an organic compound composed of synthesized inorganic chemicals that, when heated, degrades into ammonia. Because DEF is almost always combined with a specialized type of catalytic converter, an SCR system is required.
It's essentially the same concept but with a different mix of common and precious metals. This is usually combined with a particulate filter before the catalyst to remove the soot and large particles produced by conventional diesel.
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Eventually, the DEF is injected before, and sometimes directly onto, the catalyst. Based on load, the car determines how much DEF to inject, which then converts to ammonia in the hot exhaust. The ammonia in the exhaust reacts with the NOx, which is then carried into the catalyst. All of the filthy NOx and ammonia are diluted by it and exit the tailpipe as a harmless combination of water and nitrogen.
Why Is Diesel Fumes Fluid Required?
Air quality is a major concern for public health. There was a time when major cities experienced smog days and had much higher rates of respiratory disease as a result of smog. In fact, we used to put lead in fuel, which we then burned and emitted into the atmosphere, which has been shown to harm human cognition and general health.
DEF is just another step toward gradually cleaning the air of pollutants, allowing us to all breathe more simpler.
As well as, let's be honest, diesel is filthy. All of the technologies we use today are required to make non-coal rolling engines for heavy industry and light trucks viable. They were once uncommon in passenger cars, but they are now widely used in trucking. It is critical to clean up those emissions. DEF, SCR, and particulate filters do an excellent job of reducing the toxicity of extremely dirty diesel to us and the surroundings.
However, you must fill up.
Furthermore, let's face it: diesel is filthy. All of today's technologies are required to make non-coal rolling engines for heavy industry and light trucks a viable option. They were once uncommon in passenger vehicles, but are now common in trucking. Those emissions must be cleaned up. DEF, SCR, and particulate filters are extremely effective at reducing the toxicity of extremely dirty diesel to us and the environment.
However, due to modern emissions controls, most diesel will not start without DEF. If you run out of gas on the road, most vehicles will enter limp-home mode until you can refill it, then refuse to restart after shutting down. As a result, it is critical to keep filling the tank as needed and topping off for any lengthy drives.
Is It Possible to Repair Your DEF System at Home?
Well, you've unearthed that your DEF system is malfunctioning and want to know if you can repair it in your garage? It depends, but in general, no. The components of an SCR system and DEF injection are costly, and accessing the ECU for repair and calibration often necessitates the use of specialized terminals. It is some of the most expensive equipment on a diesel engine, and it is tightly secured to prevent tampering. Repairing anything with DEF usually necessitates the use of dealer-level software or a visit to a car dealership.