DEF Fluid and its Purpose
Diesel Exhaust Fluid (DEF) is a vital component in the modern diesel fuel system. DEF helps to reduce harmful emissions caused by your engine and helps diesel vehicles operate more efficiently. DEF works in combination with the exhaust after-treatment system, which uses DEF to convert nitrogen oxide (NOx) emissions into harmless nitrogen and water vapor. This process is known as selective catalytic reduction (SCR).
This specialized fluid contains a solution of urea and de-ionized water and helps to reduce NOx emissions by approximately 90%. Without DEF, diesel engines would be unable to meet current emission standards. Furthermore, DEF improves fuel economy and reduces overall operating costs.
When DEF is low or needs to be refilled, a warning light will typically appear on your dashboard. DEF fillers can be found either next to the fuel filler or under the hood, depending on your make and model of equipment. It is important to check the DEF level regularly and refill as needed, especially in commercial and off-highway vehicles.
Furthermore, DEF should never be mixed with diesel fuel, as this can cause permanent damage to the exhaust after-treatment system. This is why it is key to distinguish the DEF filler from the fuel filler. Additionally, you should avoid putting DEF to top up other fluids in your engine, as it is specifically formulated for use in diesel engines only. Mixing fluids can damage your high-pressure fuel pump, fuel injectors, as well as your fuel tank.