What does a diesel particulate filter do?

• A. Increases exhaust noise
• B. Traps and stores ash particles and other contaminants from diesel engine exhaust
• C. Lubricates moving parts
• D. Cools the exhaust

Answer: (B)

Diesel particulate filters reduce engine exhaust particulates by trapping and storing soot and other contaminants as the exhaust passes through. This captured material is then burned off during regeneration at high temperatures, while ash from lubricating oil gradually accumulates and may require cleaning or replacement. This function directly lowers particulate emissions, and it doesn’t serve to lubricate moving parts, cool the exhaust, or increase exhaust noise.