Exam 50: Servicing Maintenance of Exhaust Aftertreatment Systems

Technician A says that putting DEF into fuel tanks can void engine warranty. Technician B says that DEF is non-corrosive and will not harm painted surfaces. Who is correct?

When the SCR management circuit defaults the vehicle into a trimback mode, which of the following is the likely problem?

When using an opacitymeter to perform a J1667 smoke density test, which of the following tests would require a chassis dynamometer?

When the percentage reading increases during opacity testing of diesel engine exhaust gas, what does this indicate?

What SAE J standard relates specifically to smoke opacity measurement of highway diesel engines?

What temperature does DEF freeze at?

Technician A says that one of the most common causes of DPF failure is thermal stress during normal regeneration cycles. Technician B says that a crack in the DPF substrate immediately renders the device useless. Who is correct?

What is the maximum ambient temperature in which a valid J1667 opacity test can be undertaken?

Which of the following is the recommended method of cleaning a fouled EGR cooler core?

Technician A says that when performing a J1667 opacity test, the exhaust stack diameter must be correctly entered into the opacity meter instrument or the results will not be meaningful. Technician B says that the ambient temperature must exceed 35 degrees Fahrenheit (2 degrees Celsius) before a valid J1667 opacity test is undertaken. Who is right?

Which of the following describes how a J1667 exhaust gas, opacity meter functions?

Technician A says that any vehicle producing excessive NOx emission can be identified by performing an opacity test on its exhaust smoke. Technician B says that PM in the exhaust gas is always identified in J1667 opacity testing. Who is right?

What is the current EPA fine levied on any business or individual that either tampers with, or fails to report, tampering with any emissions control device or programming?

Technician A says that when ambient temperature drops below 35 degrees Fahrenheit (2 degrees Celsius), outdoor J1667 opacity testing on truck diesel engines does not produce meaningful datA.Technician B says that when outdoor temperatures exceed 80 degrees, a J1667 test should not be performed. Who is correct?

Which of the following is NOT a type of aneroid device used on turbo-boosted diesel engines?

Technician A says that J1677 opacity testing of a truck diesel engine in humid weather is not considered to be sufficiently reliable for compliance testing. Technician B says that most opacity meters are only accurate to 10% so retesting of marginal vehicles should be considered. Who is correct?

What is the current national maximum sulfur content permitted in a diesel fuel sold for use in commercial diesel engines in the United States or Canada?

?Technician A says that a restricted DPF does not usually trigger limp home/derate until it is 95% plugged. Technician B says that a DPF that is 95% plugged almost always has to be replaced. Who is correct?

What is a reliable tattletale that an aneroid device has been shorted out on a hydromechanical, highway truck diesel engine?

What color is the cap on a DEF reservoir?