Practice Exam Questions And Correct Answers

Automotive Service Excellence (ASE) A-Series Practice Exam Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

Covers A1–A9 (Engine Repair, Automatic Transmission/Transaxle, Manual Drivetrain, Suspension and Steering, Brakes, Electrical/Electronic Systems, Heating and Air Conditioning, Engine Performance, Light Vehicle Diesel Engines)

• A customer complains of poor fuel economy. Which of the following could

cause this condition?

• A weak fuel pump
• A faulty oxygen sensor
• A restricted air filter
• A sticking thermostat

Rationale: The oxygen sensor provides feedback for the air/fuel ratio. A

faulty sensor causes the engine to run rich, reducing fuel economy.

• / 4

• During an engine compression test, all cylinders read low. What is the

most likely cause?

• Burned exhaust valves
• Worn piston rings
• Blown head gasket between two cylinders
• Incorrect valve timing

Rationale: Worn piston rings allow compression leakage in all cylinders,

producing uniformly low readings.

3. The torque converter in an automatic transmission provides:

• Direct drive under all conditions
• Torque multiplication during acceleration
• Constant ratio drive
• Engine braking in all gears

Rationale: The converter multiplies torque when the vehicle accelerates,

allowing smooth power transfer.

• A manual transmission pops out of gear during deceleration. What is the

likely cause?

• Worn synchronizer sleeves or shift forks
• Low transmission fluid
• Worn clutch disc
• Faulty pressure plate 2 / 4

Rationale: Worn synchronizers or shift components allow gear

disengagement when torque reverses.

5. Excessive inside tire wear on both front tires indicates:

• Excessive positive camber
• Toe-out condition
• Excessive toe-in condition
• Negative camber on one side only

Rationale: Toe-in causes the inner edges of both front tires to wear

prematurely.

• The brake pedal slowly sinks to the floor under steady pressure. Which is

most likely?

• Internal leak in the master cylinder
• Air in brake lines
• Warped rotors
• Glazed pads

Rationale: A master cylinder internal bypass causes gradual loss of

hydraulic pressure.

• A car’s headlights flicker when the engine idles but brighten when revved.

The cause is likely: 3 / 4

• Weak battery
• Failing alternator diode trio
• Loose headlight ground
• Open fusible link

Rationale: Failing alternator diodes reduce output at low rpm, causing

dimming at idle.

• Air conditioning blows warm air. The compressor clutch engages, but

system pressure is low. What is likely?

• Low refrigerant charge
• Faulty compressor
• Clogged expansion valve
• Malfunctioning blend door actuator

Rationale: Low system pressure with clutch engagement indicates

insufficient refrigerant volume.

• A misfire occurs on one cylinder. Compression and spark are normal.

What should be checked next?

• Ignition coil output
• Compression again at higher speed
• Fuel injector operation
• Camshaft timing
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