Question 1

When performing an EGR system test on a vacuum operated EGR valve, how much should intake manifold vacuum decrease when the EGR valve is opened at fast idle?

Accepted Answer

A)   1-2 in. Hg.
B)   6-8 in. Hg.
C)   6-8 PSI
D)   14.7 PSIE) All of the above
F) A) and B)

Question 2

Which of the following are symptoms of a fault in the EGR system?

Accepted Answer

A)   Detonation during acceleration or cruise
B)   Rough idle and stalling
C)   Excessive NOx emissions
D)   All of theseE) A) and B)
F) A) and D) D

Question 3

A leaking evaporative system can be diagnosed using ________.

Accepted Answer

A)   Nitrogen gas and headphones
B)   A smoke machine
C)   Either of these
D)   Neither of theseE) B) and D)
F) B) and C) C

Question 4

The O2 sensors in this OBD II system are sending a voltage signal as shown. What conclusion can be made about the catalytic converter? 2 sensors in this OBD II system are sending a voltage signal as shown. What conclusion can be made about the catalytic converter?   A)  The CAT is not working correctly B)  The CAT is working correctly C)  The engine is not running, so the CAT is not functioning D)  Not enough information" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   The CAT is not working correctly
B)   The CAT is working correctly
C)   The engine is not running, so the CAT is not functioning
D)   Not enough informationE) A) and B)
F) B) and C)

Question 5

How many solenoids are contained in the GM digital EGR valve?

Accepted Answer

A)   None
B)   One
C)   Three
D)   TwoE) A) and B)
F) A) and D)

Question 6

The catalytic converter stores, then burns oxygen.

Accepted Answer

A) True 
 B)False

Question 7

A vehicle comes into the shop and the technician retrieves the diagnostic code P0401 "EGR flow insufficient." Which of these could be the cause?

Accepted Answer

A)   EGR valve stuck open
B)   Electrical wiring shorted
C)   Clogged EGR ports or passages
D)   All of these are correct.E) None of the above
F) C) and D)

Question 8

At what temperature is the catalytic converter fully effective?

Accepted Answer

A)   100 deg F
B)   1000 deg F
C)   420 deg F
D)   500 deg FE) B) and C)
F) C) and D)

Question 9

This drawing shows a catalytic converter with exhaust gases entering the CAT. What are the gases changed to at the CAT outlet? x  C)  H2O and CO2  D)  Both A and C" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   HCO and CO
B)   NOx 
C)   H2O and CO2 
D)   Both A and CE) B) and C)
F) A) and C)

Question 10

Technician A says that carbon should be cleaned out after installing a new EGR valve. Technician B cleans the EGR exhaust passages by using a stranded metal cable. Which technician is correct?

Accepted Answer

A)   Technician A only
B)   Technician B only
C)   Both technicians A and B
D)   Neither technician A nor BE) B) and C)
F) None of the above

Question 11

A vehicle failed an emission test due to high carbon monoxide and hydrocarbons in the exhaust gas. What could be the cause?

Accepted Answer

A)   Overfilling the fuel tank
B)   Saturated EVAP charcoal canister
C)   Either A or B
D)   Neither A nor BE) B) and C)
F) A) and D)

Question 12

Which type of EGR valve requires a positive exhaust system pressure to operate?

Accepted Answer

A)   Negative backpressure
B)   Digital
C)   Linear
D)   Positive backpressureE) B) and C)
F) All of the above

Question 13

Technician A says that the location of the catalytic converter is not important. Technician B says that the catalytic converter should be positioned as far from the engine as possible. Which technician is correct?

Accepted Answer

A)   Technician A only
B)   Technician B only
C)   Both technicians A and B
D)   Neither technician A nor BE) A) and B)
F) A) and C)

Question 14

The EGR system is designed to lower which exhaust emission?

Accepted Answer

A)   CO
B)   NOx 
C)   HC
D)   CO2E) A) and D)
F) B) and C)

Question 15

An electric SAI pump is controlled by ________.

Accepted Answer

A)   the PCM
B)   a vacuum switch
C)   exhaust pressure
D)   manifold vacuumE) B) and C)
F) A) and C)

Question 16

Technician A says that the electric AIR pump requires periodic maintenance. Technician B says that if the AIR pump is good, the oxygen sensors should read 850 mV or more when the AIR pump is energized. Which technician is correct?

Accepted Answer

A)   Technician A only
B)   Technician B only
C)   Both technicians A and B
D)   Neither technician A nor BE) All of the above
F) B) and C)

Question 17

The ORVR system is designed to capture ________ during re-fueling.

Accepted Answer

A)   water vapor
B)   fuel vapors
C)   excess liquid
D)   reserve fuelE) B) and C)
F) None of the above B

Question 18

An evaporative emission system leak detection pump adds ________ to the fuel tank in order to check for leaks.

Accepted Answer

A)   slight pressure
B)   pressure pulses
C)   a vacuum
D)   oxygenE) All of the above
F) None of the above

Question 19

Smog contains ________, which is an irritant to lungs and eyes.

Accepted Answer

A)   CO2 
B)   N2 
C)   O3 
D)   O2E) None of the above
F) C) and D)

Question 20

EGR is usually not required under which of these engine conditions?

Accepted Answer

A)   Idle
B)   Wide open throttle
C)   Cold engine
D)   All of these are correct.E) A) and B)
F) All of the above

Exam 27: Emission Control Devices Operation and Diagnosis

When performing an EGR system test on a vacuum operated EGR valve, how much should intake manifold vacuum decrease when the EGR valve is opened at fast idle?

Correct AnswerverifiedShow Answer

Which of the following are symptoms of a fault in the EGR system?

Correct AnswerverifiedD

A leaking evaporative system can be diagnosed using ________.

Correct AnswerverifiedC

The O2 sensors in this OBD II system are sending a voltage signal as shown. What conclusion can be made about the catalytic converter?

Correct AnswerverifiedShow Answer

How many solenoids are contained in the GM digital EGR valve?

Correct AnswerverifiedShow Answer

The catalytic converter stores, then burns oxygen.

Correct AnswerverifiedShow Answer

A vehicle comes into the shop and the technician retrieves the diagnostic code P0401 "EGR flow insufficient." Which of these could be the cause?

Correct AnswerverifiedShow Answer

At what temperature is the catalytic converter fully effective?

Correct AnswerverifiedShow Answer

This drawing shows a catalytic converter with exhaust gases entering the CAT. What are the gases changed to at the CAT outlet?

Correct AnswerverifiedShow Answer

Technician A says that carbon should be cleaned out after installing a new EGR valve. Technician B cleans the EGR exhaust passages by using a stranded metal cable. Which technician is correct?

Correct AnswerverifiedShow Answer

A vehicle failed an emission test due to high carbon monoxide and hydrocarbons in the exhaust gas. What could be the cause?

Correct AnswerverifiedShow Answer

Which type of EGR valve requires a positive exhaust system pressure to operate?

Correct AnswerverifiedShow Answer

Technician A says that the location of the catalytic converter is not important. Technician B says that the catalytic converter should be positioned as far from the engine as possible. Which technician is correct?

Correct AnswerverifiedShow Answer

The EGR system is designed to lower which exhaust emission?

Correct AnswerverifiedShow Answer

An electric SAI pump is controlled by ________.

Correct AnswerverifiedShow Answer

Technician A says that the electric AIR pump requires periodic maintenance. Technician B says that if the AIR pump is good, the oxygen sensors should read 850 mV or more when the AIR pump is energized. Which technician is correct?

Correct AnswerverifiedShow Answer

The ORVR system is designed to capture ________ during re-fueling.

Correct AnswerverifiedB

An evaporative emission system leak detection pump adds ________ to the fuel tank in order to check for leaks.

Correct AnswerverifiedShow Answer

Smog contains ________, which is an irritant to lungs and eyes.

Correct AnswerverifiedShow Answer

EGR is usually not required under which of these engine conditions?

Correct AnswerverifiedShow Answer

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D

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C

The O₂ sensors in this OBD II system are sending a voltage signal as shown. What conclusion can be made about the catalytic converter?

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B

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