Practice question

What is the purpose of Diesel Exhaust Fluid (DEF) in modern heavy-duty diesel engines?

  1. To lubricate the fuel injectors and fuel pump
  2. To increase the cetane rating and power output of diesel fuel
  3. To reduce nitrogen oxide (NOx) emissions in the exhaust system
  4. To prevent diesel fuel from waxing in cold high-altitude mountain areas

Answer: C — To reduce nitrogen oxide (NOx) emissions in the exhaust system

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