Exam 18: Exhaust Aftertreatment Systems

Technician A says that lean NOx traps (LNTs) are used by only light-duty diesel engines. Technician B says that LNTs are used by light- and heavy-duty diesel engines. Who is correct?

Which of the following will MOST LIKELY restrict gas flow through the DPF (diesel particulate filter)?

The SCR reservoir of a 2010 pickup truck has been completely depleted for more than 10 hours of driving time and the engine power has derated. Technician A says the correct service recommendation is to fill the DEF reservoir and clear associated fault codes to return the vehicle to service and full power. Technician B says the correct procedure is to fill the DEF reservoir and prime the DEF lines to remove the derate condition. Who is correct?

Which strategy will most likely be used to passively regenerate a catalyzed DPF?

A slip catalyst located after the SCR catalyst converts _________.

What operation takes place during normal engine operating conditions, when no regeneration is taking place in the NAC (nitrogen adsorbing catalysts)?

Two technicians are describing how to do a stationary regeneration. Technician A says that some SCR (selective reduction catalyst) systems can completely deplete the DEF (diesel exhaust fluid) before a fault code is set. Technician B says that after operating for more than 20 hours with depleted DEF, the vehicle will derate power. Who is right?

Diesel particulate filters, which trap soot emissions, became mandatory in:

A fully loaded DPF (diesel particulate filter) may contain ____ of soot per liter of volume capacity.

Catalyzed DPFs require oil with which of the following qualities?

Technician A says that without the pressure differential sensor (delta P sensor), the exhaust DPF would not regenerate, because the amount of soot loading would not be able to be properly calculated. Technician B says that the amount of soot loading is only estimated, and not accurately measured, using the delta P sensor. Who is correct?

Which of the following tests is used to visually verify that the SCR (selective reduction catalyst) dosing injector is flowing in the correct quantity of DEF (diesel exhaust fluid)?

The alternative to SCR (selective catalyst reduction)-liquid (SCR-L) systems using DEF was to manufacture:

Which process is used to clean ash from a DPF?

The hydrogen and carbon molecules in gasoline need oxygen to completely burn in a stoichiometric ratio of:

A conventional oxidation catalytic converter found on a gasoline-fueled vehicle requires exhaust temperatures as high as ____ for catalysts to operate effectively.

To prevent adding diesel fuel to DEF (diesel exhaust fluid), the filler tube has a designated:

Which of the following particles that cannot be regenerated does NOT end up in the DPF (diesel particulate filter)?

What is the ammonia (NH3) compound DEF (diesel exhaust fluid) called that is essential to SCR (selective catalyst reduction) system operation?

Technician A says that the DEF (diesel exhaust fluid) reservoir will need to be filled with a minimum amount of fluid to operate above idle until the diesel exhaust fluid tank has been refilled. Technician A says that once the DEF level becomes critical, the engine will shut down. Who is right?