ASE L1 Domain 5: Emission Control Systems Diagnosis Welcome to your ASE L1 Domain 5: Emission Control Systems Diagnosis 1. ASE L1: Emission Control Systems Diagnosis A vehicle equipped with a Tier 2 bin 5 emissions standard is displaying a P0420 code, indicating catalytic converter efficiency below threshold. What is the MOST likely cause for this fault code? A. Degraded oxygen sensor response. B. Exhaust manifold leak. C. Contaminated fuel injector. D. Catalyst substrate meltdown. None 2. ASE L1: Emission Control Systems Diagnosis During a NOx (oxides of nitrogen) emissions test, a vehicle fails due to higher than allowable NOx levels. The most effective diagnosis step to identify the cause is: A. Checking the coolant temperature sensor readings. B. Inspecting the EGR system for proper operation. C. Testing the oxygen sensor switching rate. D. Verifying the operation of the catalytic converter. None 3. ASE L1: Emission Control Systems Diagnosis A vehicle with a variable valve timing (VVT) system has been diagnosed with a P0010 code, "A" Camshaft Position Actuator Circuit (Bank 1). The MOST likely cause of this would be: A. Faulty camshaft position sensor. B. Clogged oil passage in the VVT actuator. C. Worn timing chain. D. Open or short in the VVT solenoid circuit. None 4. ASE L1: Emission Control Systems Diagnosis A vehicle's EVAP system has repeatedly failed the self-test for sealing. The MOST likely cause is: A. A defective canister purge valve. B. A loose fuel cap. C. A faulty EVAP pressure sensor. D. A leaking EVAP system hose. None 5. ASE L1: Emission Control Systems Diagnosis When diagnosing an emission failure due to high HC (hydrocarbons), which of the following should be checked FIRST? A. The condition of the ignition wires. B. The operation of the O2 sensors. C. The air filter's serviceability. D. The integrity of the exhaust system. None 6. ASE L1: Emission Control Systems Diagnosis A technician is diagnosing a vehicle with an active P0401 (Exhaust Gas Recirculation Flow Insufficient Detected code). The technician should investigate: A. The EGR valve for sticking closed. B. The catalytic converter for blockage. C. The O2 sensor for a lean mixture. D. The intake manifold for a vacuum leak. None 7. ASE L1: Emission Control Systems Diagnosis The air injection reaction (AIR) system is being inspected on a vehicle after a P0410 (Secondary Air Injection System Malfunction) code was set. What is the FIRST component a technician should check? A. The secondary air injection pump. B. The one-way check valves. C. The system's relay. D. The fuse to the AIR pump. None 8. ASE L1: Emission Control Systems Diagnosis A technician finds a P0455 (Evaporative Emission Control System Leak Detected - gross leak) code stored in a vehicle's computer. The most appropriate initial diagnostic step is to: A. Use a smoke machine to locate the leak. B. Replace the fuel cap. C. Conduct a purge valve operational test. D. Inspect the charcoal canister for damage. None 9. ASE L1: Emission Control Systems Diagnosis If a vehicle with an advanced emission control system is running rich and emitting black smoke from the exhaust, what could be a potential cause? A. A faulty MAP sensor sending incorrect manifold pressure information. B. An overcharged air conditioning system. C. A depleted battery. D. An improperly installed windshield affecting aerodynamics. None 10. ASE L1: Emission Control Systems Diagnosis What would be a likely result of a defective PCV (Positive Crankcase Ventilation) valve that is stuck open? A. High engine idle speed. B. Decreased engine oil level. C. Increased fuel consumption. D. Reduced engine cooling efficiency. None 1 out of 10 Time is Up! Time's up
