Exhaust Diesel Exhaust & DPF Systems

Question 1

What does DPF stand for in diesel vehicle exhaust systems?

Accepted Answer

Diesel Particulate Filter

Answer

Diesel Power Filter

Answer

Direct Purge Filter

Answer

Dual Pressure Flap

Question 2

What initiates an 'active regeneration' cycle in a diesel DPF system?

Accepted Answer

ECU detecting that soot load has reached a threshold and injecting extra fuel to raise exhaust temperatures

Answer

Driver manually pressing a regeneration button

Answer

Opening of the EGR valve to allow hot gases to burn the soot

Answer

A coolant temperature-triggered post-injection event at startup

Question 3

What warning should a diesel driver heed to prevent DPF damage?

Accepted Answer

Avoid frequent short trips that prevent the DPF from reaching regeneration temperatures

Answer

Avoid driving at highway speeds

Answer

Avoid using diesel fuel above B5 blend

Answer

Avoid towing, as it increases soot production too rapidly

Question 4

What is 'DPF delete' and why is it illegal for street use in the US?

Accepted Answer

Physically removing the DPF; it is illegal because it violates federal emissions laws

Answer

Cleaning the DPF chemically; it is illegal because it voids the warranty

Answer

Reprogramming the ECU to skip DPF monitoring; it is a grey area

Answer

Replacing the DPF with a high-flow version; it is only illegal in California

Question 5

What is 'passive DPF regeneration'?

Accepted Answer

The DPF self-cleans during normal highway driving when exhaust temperatures are naturally high enough

Answer

A scheduled DPF cleaning performed at the dealership every 30,000 miles

Answer

A chemical injection system that dissolves soot at low temperatures

Answer

A vacuum-based system that removes soot without burning

Question 6

What additive is sometimes used in European diesel systems to lower the soot ignition point and assist DPF regeneration?

Accepted Answer

Fuel-borne catalyst (FBC) containing cerium or iron

Answer

AdBlue (urea solution)

Answer

Diesel exhaust fluid (DEF)

Answer

Cetane improver additive