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1. While servicing a vehicle, you retrieve the diagnostic code P0401, “EGR (exhaust gas recirculation) flow insufficient.” Which of these is the most likely cause?
A. Electrical wiring shorted to voltage
B. Stuck-open EGR valve
C. Clogged EGR ports or passages
D. Electrical wiring shorted to ground
2. Oxides of nitrogen (NOx) contribute to the formation of
A. high levels of CO2.
B. particulate emissions.
C. photochemical smog.
D. acid rain.
Technician A says that manually opening an exhaust gas recirculation (EGR) valve with a vacuum pump or scan tool will cause the engine to idle roughly or stall. Technician B says that blocking the EGR valve passages will have no effect on the OBD-II. Who is correct?
A. Technician A
B. Technician B
C. Neither Technician A nor B
D. Both Technicians A and B
4. Oxygen combines with nitrogen in the air to form NOx at about _______ °F.
A. 2500
B. 000
C. 50
D. 1500
5. Technician A says that a 3 × 5 card should be held against the oil fill opening if the positive crankcase ventilation (PCV) system is operating correctly. Technician B says that if a PCV valve rattles, it’s working properly. Who is correct?
A. Neither Technician A nor B
B. Both Technicians A and B
C. Technician A
D. Technician B
6. Which of these items will least likely increase pressure in the evaporative emission control system?
A. Inlet fuel to the fuel pump
B. Returned fuel from the fuel-injection system
C. Fuel temperature
D. Volatility of the fuel
7. The OBD-II catalytic converter monitor uses _______ sensor(s) to monitor catalytic converter efficiency.
A. front and rear O2
B. a throttle position
C. front and rear catalyst temperature
D. an engine coolant temperature
8. Which one of the following is a prime source of problems in secondary air systems?
A. Engine coolant
B. Engine oil
C. Water
D. Dirt
9. Which of these engine concerns may be caused by a stuck-open exhaust gas recirculation (EGR) valve?
A. Engine missing at highway speed
B. Ping (spark knock or detonation)
C. Excessive NOx exhaust emissions
D. Rough idle/stalling
10. Oxides of nitrogen result from a combination of nitrogen and
A. oxygen.
B. carbon.
C. hydrogen.
D. argon.
11. A technician suspects that the exhaust gas recirculation (EGR) valve is closed. Which of the following would indicate a closed EGR valve?
A. Engine surge
B. Rough idle
C. Stalling
D. Spark knock
12. Which of the following exhaust gases are least likely to be measured in percentages?
A. HC (hydrocarbon)
B. CO (carbon monoxide)
C. CO2 (carbon dioxide)
D. O2 (oxygen)
13. Which of these items is least likely to cause an exhaust emissions test failure as a result of excessive NOx emissions?
A. Defective fuel injector
B. Defective oxygen sensor
C. Poor flow through the EGR system
D. Spark plug hot range
14. Technician A says that a converter that rattles when tapped with a mallet should be replaced. Technician B says that the root cause of a converter failure should be diagnosed and repaired before a replacement converter is installed. Who is correct?
A. Technician B
B. Neither Technician A nor B
C. Technician A
D. Both Technicians A and B
15. A scan tool check of the canister purge valve control solenoid shows that it’s always open. Which of the following could be the cause?
A. Vacuum passage restriction
B. Vacuum source problem
C. Defective powertrain control module (PCM)
D. Broken diaphragm
16. What term describes a catalytic converter as it reaches its effective temperature?
A. Light-off
B. Firing
C. Initiation
D. Consumption
17. Technician A says that the location of the catalytic converter isn’t important. Technician B says that the catalytic converter should be positioned as far away from the engine as possible. Who is correct?
A. Both Technicians A and
B. Technician B
C. Neither Technician A nor B
D. Technician A