ASE X1 Domain 2: Emissions Systems Diagnosis Welcome to your ASE X1 Domain 2: Emissions Systems Diagnosis 1. ASE X1: Emissions Systems Diagnosis A vehicle with an OBD-II system has a Diagnostic Trouble Code DTC for a "slow response from oxygen sensor bank 1 sensor 2." Which of the following could be the cause? A. A vacuum leak in the intake manifold. B. Contaminated fuel injectors. C. A leaking exhaust manifold gasket before the sensor. D. An aged or contaminated oxygen sensor. None 2. ASE X1: Emissions Systems Diagnosis What would most likely cause an increase in Nox emissions on a vehicle equipped with EGR? A. A malfunctioning EGR valve stuck closed. B. A malfunctioning EGR valve stuck open. C. Excessive fuel pressure. D. A defective oxygen sensor. None 3. ASE X1: Emissions Systems Diagnosis When diagnosing an evaporative emissions system, which of the following is NOT a common method used to locate a leak? A. Using an ultraviolet dye and UV light. B. Applying smoke and looking for it to escape. C. Listening for a hissing sound at the fuel cap. D. Measuring voltage drop across the EVAP purge valve. None 4. ASE X1: Emissions Systems Diagnosis A vehicle repeatedly sets a DTC for "Insufficient Catalytic Converter Efficiency." What is the least likely cause? A. The use of leaded gasoline. B. A failing upstream oxygen sensor. C. An aftermarket high-flow catalytic converter. D. A deteriorated thermostat causing low engine temperatures. None 5. ASE X1: Emissions Systems Diagnosis A technician is unable to communicate with the vehicle's PCM while attempting an OBD-II scan. All other vehicle systems appear to function normally. What is the most likely cause? A. A blown fuse in the auxiliary power circuit. B. A faulty manifold absolute pressure sensor. C. An open in the serial data communication line. D. A malfunctioning mass air flow sensor. None 6. ASE X1: Emissions Systems Diagnosis During a pre-OBD-II emissions failure diagnosis, a technician observes that the CO levels are high while the HC and Nox readings are normal. What could be a potential cause? A. Inoperative catalytic converter. B. Faulty ignition system. C. Improper air/fuel mixture. D. Inadequate EGR flow. None 7. ASE X1: Emissions Systems Diagnosis A vehicle is found to have high hydrocarbon HC emissions at idle but normal readings at higher RPMs. What is the most likely cause? A. Excessive exhaust backpressure. B. A defective catalytic converter. C. Intermittent misfires due to a faulty ignition coil. D. Lean fuel condition caused by a vacuum leak. None 8. ASE X1: Emissions Systems Diagnosis If a vehicle's Check Engine light comes on and the code indicates a failure in the secondary air injection system, what could be the consequence if left unrepaired? A. Reduced acceleration performance. B. Higher than normal fuel consumption. C. Increased emissions during cold starts. D. Frequent misfires across all cylinders. None 9. ASE X1: Emissions Systems Diagnosis A vehicle's engine performance is poor and the MIL is illuminated. The scan tool reveals a DTC for the fuel tank pressure sensor. Which of the following is NOT a likely diagnostic step? A. Checking for a cracked or disconnected hose in the EVAP system. B. Testing the fuel tank pressure sensor voltage signal. C. Inspecting the integrity of the fuel tank and its components. D. Performing a cylinder compression test. None 10. ASE X1: Emissions Systems Diagnosis During a state emissions test, a vehicle fails due to high Nitrogen Oxide (Nox) levels. The vehicle does not have an EGR system. What is the next best step to diagnose the cause? A. Check the air filter for clogging. B. Inspect the operation of the thermostat and cooling system. C. Test the fuel injectors for proper atomization. D. Verify the proper operation of the oxygen sensors. None 1 out of 10 Time is Up! Time's up
