Free ASE Light Vehicle Diesel Engines (A9) Certification Test Practice Questions

Sample Practice Questions

Try these 10 sample questions from the ASE Light Vehicle Diesel Engines (A9) Certification Test practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1A light vehicle diesel has an intermittent rough-running complaint, but the operating conditions are unclear. Which action best establishes the concern before selecting a diagnostic test?

   1. A. Replace the fuel filter before reproducing the concern.
   2. B. Verify the complaint and review the driver's concerns and service history.
   3. C. Clear any stored codes before recording operating data.
   4. D. Perform a cylinder-head teardown before checking the vehicle.

   Answer: B

   Explanation: The A9 task list says to "Verify the complaint, and road/dyno test vehicle; review driver/customer concerns/expectations and vehicle service history (if available); determine further diagnosis." Establishing the reported condition and history guides the next test; the other actions assume a cause before verification.

   Reference: ASE Automobile Study Guide — p. 50, A9 General Diagnosis task 1

2. 2A 2023 Ford 6.7L diesel cylinder head has been removed. Which M12 head-bolt decision follows the manufacturer's design description?

   1. A. Reuse the bolts if their threads look clean.
   2. B. Reuse the bolts after reducing the torque.
   3. C. Replace the torque-to-yield M12 bolts.
   4. D. Replace only bolts from the left cylinder head.

   Answer: C

   Explanation: The manufacturer states, "The M12 cylinder head bolts are torque-to-yield bolts, and cannot be reused." This controls the specified cylinder-head or valve-train decision; the other choices confuse neighboring components or omit the necessary inspection or repair.

   Reference: 2023 6.7L Power Stroke V8 Turbo Diesel Engine — p. 14, Cylinder Heads

3. 3A 2023 Ford 6.7L diesel piston-cooling jet is being inspected. Where does it direct pressurized oil?

   1. A. Into a hole at the bottom of each piston.
   2. B. Across the cylinder wall above each piston.
   3. C. Onto the piston ring pack near top dead center.
   4. D. Into an oil hole in each connecting-rod cap.

   Answer: A

   Explanation: Ford's 2023 diesel guide states, "Individual block-mounted oil jets spray pressurized oil into a hole in the bottom of each piston." The specified component and condition therefore match the selected option; the alternatives confuse the part's location, orientation, function, or service limitation.

   Reference: 2023 6.7L Power Stroke V8 Turbo Diesel Engine — p. 17, Pistons

4. 4A 2023 Ford 6.7L has a charge-air cooler temperature concern but normal primary engine coolant temperature. Which system should be evaluated for the charge-air cooler?

   1. A. The independent secondary cooling system.
   2. B. The primary engine cooling circuit only.
   3. C. The engine-oil lubrication circuit only.
   4. D. The fuel return circuit only.

   Answer: A

   Explanation: Ford's service guide states, "The powertrain secondary cooling system, a low temperature system that cools the Charge Air Cooler (CAC), fuel cooler, Diesel Exhaust Fluid (DEF) injector" This identifies the correct cooling-system component, flow path, or control for the specified engine; the other choices misidentify a neighboring circuit or control.

   Reference: 2023 6.7L Power Stroke V8 Turbo Diesel Engine — p. 25, Engine Cooling System

5. 5A 2023 Ford 6.7L air cleaner reaches maximum restriction. What operating effect does Ford associate with that condition?

   1. A. Reduced engine performance and fuel economy.
   2. B. Increased engine performance and fuel economy.
   3. C. Unchanged performance with higher fuel economy.
   4. D. Higher power with unchanged fuel economy.

   Answer: A

   Explanation: Ford's air-management guide states, "Engine performance and fuel economy are adversely affected when maximum restriction of the air cleaner element is reached." That operating relation identifies the selected sensor, component role, or diagnostic effect; the other choices misassign the function.

   Reference: 2023 6.7L Power Stroke V8 Turbo Diesel Engine — p. 47, Air Flow - Intake Side

6. 6On a 2023 Ford 6.7L common-rail diesel, what does the electric in-tank pump do when the key is turned on before cranking?

   1. A. Pressurizes the low-pressure fuel system.
   2. B. Pressurizes the common rail to full injection pressure.
   3. C. Injects fuel directly into each cylinder.
   4. D. Opens the exhaust downstream injector.

   Answer: A

   Explanation: Ford's low-pressure fuel-system text states, "At key on, the electric fuel pump within the main fuel tank is powered on, pressurizing the low-pressure fuel system." This controls the specified fuel-flow, filtration, warning, or protection decision; the other options confuse high-pressure injection or another circuit.

   Reference: 2023 6.7L Power Stroke V8 Turbo Diesel Engine — p. 67, Fuel System Operation

7. 7Before using service literature for a diesel engine, which vehicle information should a technician identify to select applicable precautions and bulletins?

   1. A. The VIN and engine model, calibration, and serial numbers.
   2. B. The VIN and model year, without the engine calibration or serial number.
   3. C. The engine model and VIN, without its calibration or serial number.
   4. D. The engine serial number and model year, without VIN or calibration.

   Answer: A

   Explanation: The official task list directs technicians to "Record vehicle identification number (VIN). Identify engine model, calibration and serial numbers to research applicable vehicle and service information, service precautions, and technical service bulletins; determine needed actions." These identifiers control which information applies.

   Reference: ASE Automobile Study Guide — p. 50, A9 General Diagnosis task 2

8. 8A technician has a 2023 Ford 6.7L cylinder head that looks like a head from an earlier model year. What compatibility check is necessary before installation?

   1. A. Treat the heads as interchangeable because their appearance is similar.
   2. B. Verify the 2023 head is used only with a compatible 2023 application.
   3. C. Use an earlier head if its valve-cover color matches.
   4. D. Interchange either head if the bolt holes appear aligned.

   Answer: B

   Explanation: The manufacturer states, "they are not compatible with previous model years." This controls the specified cylinder-head or valve-train decision; the other choices confuse neighboring components or omit the necessary inspection or repair.

   Reference: 2023 6.7L Power Stroke V8 Turbo Diesel Engine — p. 14, Cylinder Heads note

9. 9A cracked-type connecting rod and cap from a 2023 Ford 6.7L have been separated for inspection. How should they be assembled?

   1. A. Match the original rod and cap and preserve orientation.
   2. B. Match any cap with the same nominal bore diameter.
   3. C. Rotate the cap to move worn surfaces away from load.
   4. D. Use a cap from a different rod if its bolt holes align.

   Answer: A

   Explanation: Ford's 2023 diesel guide states, "Make sure the connecting rod and cap are installed as a set or engine damage may occur. Proper orientation of the connecting rod and cap is also critical." The specified component and condition therefore match the selected option; the alternatives confuse the part's location, orientation, function, or service limitation.

   Reference: 2023 6.7L Power Stroke V8 Turbo Diesel Engine — p. 17, Connecting Rods

10. 10On a 2023 Ford 6.7L, which cooling system serves the EGR cooler?

    1. A. The primary engine cooling system.
    2. B. The secondary charge-air cooling system.
    3. C. The fuel return cooling loop.
    4. D. The engine-oil cooler circuit alone.

    Answer: A

    Explanation: Ford's service guide states, "The EGR cooler uses the primary cooling system to reduce exhaust gas temperatures." This identifies the correct cooling-system component, flow path, or control for the specified engine; the other choices misidentify a neighboring circuit or control.

    Reference: 2023 6.7L Power Stroke V8 Turbo Diesel Engine — p. 25, Engine Cooling System