We use Diesel Exhaust Fluid (DEF) in modern diesel vehicles primarily to significantly reduce harmful emissions, ensuring they meet strict environmental regulations.
Reducing Harmful Emissions
One of the main purposes of DEF is to make sure it doesn't emit high levels of nitrogen oxide into the atmosphere. Nitrogen oxides (NOx) are pollutants that contribute to smog and acid rain. By using DEF, diesel engines can drastically lower the amount of NOx released into the air, making them more environmentally friendly.
Meeting Regulatory Standards
The use of DEF is crucial for compliance. Without DEF, your diesel vehicle would violate the federal emissions standards set by the EPA. These standards are put in place to protect air quality. Vehicles equipped with Selective Catalytic Reduction (SCR) systems require DEF to operate correctly and meet these mandatory emissions limits.
How DEF Works (Simplified)
Diesel Exhaust Fluid is a non-toxic solution of 67.5% purified water and 32.5% automotive-grade urea. It is injected into the exhaust stream before the gases enter a component called the Selective Catalytic Reduction (SCR) catalyst. Inside the SCR system, the DEF undergoes a chemical reaction that converts the harmful nitrogen oxides (NOx) into harmless nitrogen gas and water vapor.
Practical Implications of Not Using DEF
Running a diesel vehicle that requires DEF without the fluid has several important consequences:
- Violation of Emissions Standards: The vehicle will emit high levels of NOx and fail to meet required environmental regulations, potentially leading to inspection failures or fines.
- Vehicle Performance Issues: Modern diesel vehicles are designed with the SCR system and DEF as integral parts of their emission control. The vehicle's computer (ECU) monitors DEF levels.
- Inability to Start: As a compliance measure, most diesel vehicles that require DEF are programmed to prevent starting if the DEF tank is empty. As the reference states, "If you run out of DEF, your diesel vehicle may not start."
In summary, DEF is a vital component in modern diesel vehicles, essential for controlling harmful nitrogen oxide emissions, complying with federal regulations, and ensuring proper vehicle operation.
