ASE T1 Domain 7: Emissions Control Systems Diagnosis and Repair Welcome to your ASE T1 Domain 7: Emissions Control Systems Diagnosis and Repair 1. ASE T1: Emissions Control Systems Diagnosis and Repair When diagnosing an EVAP system that consistently fails to hold vacuum during a smoke test, which of the following is LEAST likely to be the cause? A. Defective canister purge valve B. Leaking fuel tank pressure sensor C. Cracked EVAP system hose D. Malfunctioning vent solenoid None 2. ASE T1: Emissions Control Systems Diagnosis and Repair What could be a possible cause for a vehicle that displays a DTC for insufficient EGR flow? A. Excessive backpressure from a restricted exhaust B. A malfunctioning EGR temperature sensor C. An over-performing catalytic converter D. A blocked EGR inlet passage None 3. ASE T1: Emissions Control Systems Diagnosis and Repair If a vehicle with a secondary air injection system is found to have high CO and HC emissions at idle, but normal readings at higher RPMs, what is the most likely cause? A. Faulty air injection pump B. Defective one-way check valve C. Malfunctioning air bypass solenoid D. Clogged air injection ports None 4. ASE T1: Emissions Control Systems Diagnosis and Repair A vehicle's PCM is setting a code for the catalytic converter efficiency below threshold. What should be checked first? A. The front O2 sensor for proper operation B. The rear O2 sensor for proper operation C. Exhaust manifold for cracks D. Ignition timing None 5. ASE T1: Emissions Control Systems Diagnosis and Repair Which condition can cause a vehicle to fail a NOx emissions test? A. Lean fuel mixture B. Coolant temperature too low C. EGR system not functioning D. All of the above None 6. ASE T1: Emissions Control Systems Diagnosis and Repair A technician is troubleshooting a P0442 "EVAP System Small Leak Detected" code. Which of the following is NOT a step in the diagnostic procedure? A. Smoke test the EVAP system B. Check the fuel cap for proper sealing C. Inspect the EVAP purge valve operation D. Verify proper fuel octane rating None 7. ASE T1: Emissions Control Systems Diagnosis and Repair During an emissions diagnosis, a technician finds that the EGR valve is receiving vacuum at idle. What is the most likely cause? A. Faulty EGR valve B. EGR vacuum modulator defect C. Vacuum hose routing error D. PCM software in need of an update None 8. ASE T1: Emissions Control Systems Diagnosis and Repair Which of the following components, if defective, is most likely to cause an increase in tailpipe emissions of hydrocarbons HC? A. Throttle position sensor B. Engine coolant temperature sensor C. Positive crankcase ventilation (PCV) valve D. Manifold absolute pressure (MAP) sensor None 9. ASE T1: Emissions Control Systems Diagnosis and Repair A vehicle is experiencing poor fuel economy and the diagnostic code for the oxygen sensor heater circuit is active. The least likely cause of this issue would be: A. A blown fuse for the O2 sensor heater circuit B. An open in the O2 sensor heater circuit wiring C. A malfunctioning oxygen sensor D. A defective throttle body None 10. ASE T1: Emissions Control Systems Diagnosis and Repair If a vehicle exhibits a DTC for the EGR temperature sensor circuit high voltage, which of the following is an unlikely cause? A. Short to voltage in the EGR temperature sensor circuit B. Faulty EGR temperature sensor C. Disconnected EGR temperature sensor connector D. Corroded EGR temperature sensor terminal None 1 out of 10 Time is Up! Time's up
