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This 50-question multiple-choice practice test is designed to help you prepare for the ASE (Automotive Service Excellence) certification exam.
Questions are based on real-world automotive diagnostics, repair procedures, and safety protocols.
Read each question carefully and choose the best possible answer.
Good luck!
ASE Automotive Technician Certification Practice Test
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Your answers are highlighted below.
Question 1 |
Which component is responsible for igniting the air-fuel mixture in a gasoline engine?
Fuel injector | |
Alternator | |
Spark plug | |
Oxygen sensor |
Question 2 |
What is the primary function of the catalytic converter?
Reduce exhaust noise | |
Increase engine horsepower | |
Lower harmful emissions | |
Improve fuel economy |
Question 3 |
A worn CV joint typically produces what kind of noise during a turn?
Whistling | |
Clicking | |
Humming | |
Popping |
Question 4 |
What tool is used to measure cylinder bore wear?
Feeler gauge | |
Vernier caliper | |
Micrometer | |
Dial bore gauge |
Question 5 |
A brake rotor that is warped will most likely cause:
Loss of braking power | |
A high-pitched squeal | |
Pulsation in the brake pedal | |
Grinding noise |
Question 6 |
What system controls the fuel injection timing and amount?
EGR system | |
Transmission control module | |
Engine control module | |
Crankcase ventilation |
Question 7 |
What does OBD-II stand for?
Over Boost Device | |
On-Board Diagnostics | |
Output Brake Device | |
Overhead Balance Distributor |
Question 8 |
Which battery test checks for current leakage?
Open circuit voltage test | |
Parasitic draw test | |
Load test | |
Specific gravity test |
Question 9 |
A vehicle pulls to one side when braking. What is the most likely cause?
Worn struts | |
Uneven tire wear | |
Sticking brake caliper | |
Bad CV axle |
Question 10 |
What tool measures alternator output?
Timing light | |
Hydrometer | |
Voltmeter | |
Torque wrench |
Question 11 |
What part of the suspension system cushions the ride and controls spring motion?
Leaf spring | |
Control arm | |
Shock absorber | |
Ball joint |
Question 12 |
What causes the check engine light to illuminate?
Blown head gasket | |
Open hood | |
Fault detected by ECM | |
Faulty window regulator |
Question 13 |
What is the most likely result of a lean air-fuel mixture?
High HC emissions | |
Rough idle | |
Black smoke | |
Rich condition |
Question 14 |
What component controls the gear shifting in an automatic transmission?
Radiator | |
Shift solenoid | |
Fuel Injector | |
Power steering pump |
Question 15 |
What is the first step in diagnosing an engine noise complaint?
Remove the oil pan | |
Disconnect the battery | |
Listen and locate the source | |
Change the spark plugs |
Question 16 |
What causes white exhaust smoke?
Burning oil | |
Rich fuel mixture | |
Coolant entering the combustion chamber | |
Faulty fuel pressure regulator |
Question 17 |
A slipping serpentine belt can cause:
Low fuel pressure | |
Loss of power steering | |
Valve noise | |
Wheel misalignment |
Question 18 |
What part is used to adjust toe-in and toe-out in an alignment?
Lower control arm | |
Tie rod | |
Stabilizer bar | |
Ball joint |
Question 19 |
What component amplifies the low-voltage signal in the ignition system?
Crank sensor | |
Ignition coil | |
Distributor cap | |
Camshaft |
Question 20 |
If a fuse repeatedly blows, what should be checked first?
Battery voltage | |
Grounding strap | |
Wiring short | |
Ignition key |
Question 21 |
What condition may result from a stuck-open thermostat?
Overheating | |
Poor gas mileage | |
Engine not reaching operating temp | |
Misfire |
Question 22 |
What does the EGR valve do?
Reduces fuel pressure | |
Lowers combustion temperatures | |
Cools radiator fluid | |
Controls ignition timing |
Question 23 |
What does a clogged air filter most directly affect?
Alternator output | |
Engine compression | |
Air-fuel ratio | |
Transmission fluid level |
Question 24 |
A vacuum leak may result in:
Low oil pressure | |
High idle speed | |
Dead battery | |
Coolant leak |
Question 25 |
A vehicle has a bouncing ride. What’s likely worn?
Brake pads | |
Spark plugs | |
Shock absorbers | |
Battery |
Question 26 |
What is the main function of a mass airflow (MAF) sensor?
Detect spark timing | |
Measure air entering ethe ngine | |
Regulate fuel pressure | |
Monitor crank position |
Question 27 |
What condition causes brake fade?
Low tire pressure | |
Brake overheating | |
Frozen caliper | |
Oil on rotors |
Question 28 |
What test checks for combustion gases in the cooling system?
Block test | |
Oil pressure test | |
Compression test | |
Vacuum test |
Question 29 |
What component opens the intake and exhaust valves?
Crankshaft | |
Timing chain | |
Camshaft | |
Piston |
Question 30 |
What sensor determines engine speed?
Knock sensor | |
MAF sensor | |
Crankshaft position sensor | |
TPS sensor |
Question 31 |
What is the result of a failing O2 sensor?
Engine overheating | |
Oil contamination | |
Poor fuel economy | |
Loud exhaust |
Question 32 |
What causes uneven tire wear?
Faulty battery | |
Low transmission fluid | |
Misalignment | |
Weak ignition coil |
Question 33 |
What is the primary purpose of motor oil?
Clean the fuel injectors | |
Prevent overheating | |
Lubricate engine parts | |
Increase compression |
Question 34 |
What component converts mechanical energy into electrical energy?
Starter | |
Ignition coil | |
Alternator | |
Radiator fan |
Question 35 |
What component stores and releases voltage in the ignition system?
Battery | |
Capacitor | |
Coil pack | |
Igniter |
Question 36 |
If the radiator is low but no external leaks are found, what is a possible cause?
Clogged air filter | |
Leaking head gasket | |
Stuck EGR valve | |
Slipping clutch |
Question 37 |
What test is used to check cylinder compression?
Fuel pressure test | |
Leak-down test | |
Compression test | |
Vacuum test |
Question 38 |
A hissing sound from under the hood often indicates:
Valve tick | |
Vacuum leak | |
Belt slip | |
Timing issue |
Question 39 |
What part transfers engine torque to the wheels?
Radiator | |
Fuel tank | |
Transmission | |
Steering rack |
Question 40 |
What is the purpose of an oil filter?
Measure oil pressure | |
Clean contaminants from oil | |
Add viscosity | |
Reduce oil temperature |
Question 41 |
What is a symptom of worn brake pads?
High idle | |
Clunking on bumps | |
Squealing noise when braking | |
Battery light on |
Question 42 |
The power steering pump is driven by:
Electrical current | |
Belt | |
Vacuum | |
Hydraulic pressure |
Question 43 |
What’s the function of the fuel pressure regulator?
Adjust tire pressure | |
Maintain consistent fuel pressure | |
Increase octane | |
Reduce emissions |
Question 44 |
What is used to maintain battery voltage while the engine is running?
Voltage regulator | |
Starter | |
Inverter | |
Ignition module |
Question 45 |
What tool tests the coolant freezing point?
Thermocouple | |
Radiator pressure tester | |
Hydrometer | |
Refractometer |
Question 46 |
If the steering wheel shakes at highway speeds, what is the likely cause?
Engine misfire | |
Low oil pressure | |
Wheel imbalance | |
Dead battery |
Question 47 |
What is indicated by blue exhaust smoke?
Rich fuel mix | |
Coolant leak | |
Burning oil | |
Normal ope |
Question 48 |
Which component controls the engine temperature?
Radiator cap | |
Fan belt | |
Thermostat | |
Heater core |
Question 49 |
What part reduces the amount of voltage from the battery to the sensors?
Resistor | |
Ignition switch | |
Ground wire | |
Voltage regulator |
Question 50 |
What’s the function of a PCV valve?
Pressurize coolant | |
Recycle crankcase gases | |
Control exhaust | |
Adjust fuel trim |
Once you are finished, click the button below. Any items you have not completed will be marked incorrect.
There are 50 questions to complete.
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