ASE - Automotive Service Excellence Practice Test #2 1 — Questions and Answers
Question 1: A technician is diagnosing a no-start condition on a gasoline engine. The engine cranks normally but will not fire. Spark is confirmed at all cylinders. What should be tested NEXT?
- Ignition coil primary resistance
- Fuel pressure at the rail (Correct answer)
- Crankshaft position sensor signal
- Throttle position sensor voltage
Correct answer: Fuel pressure at the rail
With spark confirmed, the next logical step is to verify fuel delivery. Low or no fuel pressure at the rail will prevent combustion even when ignition is functioning correctly. Fuel pressure testing quickly isolates whether the fault is in the fuel system before chasing electrical components.
Question 2: A customer reports that the brake pedal slowly sinks to the floor when held at a stop, but brake performance otherwise feels normal. What is the MOST likely cause?
- Air in the brake lines
- Worn front brake pads
- Internal leak in the master cylinder (Correct answer)
- Stuck brake caliper piston
Correct answer: Internal leak in the master cylinder
A pedal that sinks under steady pressure but recovers when released and re-applied is the classic symptom of an internal master cylinder bypass. The seals allow fluid to slip past under sustained load, causing the gradual loss of pedal height without any external fluid leak.
Question 3: When measuring battery voltage with a digital multimeter on a fully charged 12-volt automotive battery at rest (no load), what reading should the technician expect?
- 11.8 – 12.0 V
- 12.2 – 12.4 V
- 12.6 – 12.8 V (Correct answer)
- 13.5 – 14.5 V
Correct answer: 12.6 – 12.8 V
A fully charged 12-volt lead-acid battery at rest (surface charge dissipated) reads approximately 12.6 – 12.8 V. Readings below 12.4 V indicate a partially discharged battery, while 13.5 – 14.5 V is the normal charging system output seen with the engine running.
Question 4: A rear-wheel drive vehicle pulls strongly to the right during braking. All four tires are properly inflated. What is the MOST likely cause?
- A seized right rear wheel bearing
- A sticking left front brake caliper (Correct answer)
- Worn rear shock absorbers
- A loose right front strut mount
Correct answer: A sticking left front brake caliper
Brake pull occurs toward the side with MORE braking force. A sticking (dragging) left front caliper can cause uneven braking, but a caliper that is seized OPEN (not applying) on the left would reduce braking on that side, pulling the vehicle toward the right where braking force is greater. This is the most common single-component cause of brake pull.
Question 5: While performing a cooling system pressure test, the technician pressurizes the system to the cap rating and observes the gauge slowly dropping over five minutes with no visible external leaks. What is the MOST likely cause?
- A faulty radiator cap
- A leaking intake manifold gasket or head gasket (Correct answer)
- A cracked coolant reservoir
- A weak water pump impeller
Correct answer: A leaking intake manifold gasket or head gasket
If pressure drops with no external leak visible, coolant is escaping internally — most commonly through a failed head gasket or intake manifold gasket into the combustion chamber or oil passages. External leaks at hoses, the radiator, or the reservoir would be visible on inspection.
Question 6: A technician uses an OBD-II scanner and finds a P0420 code — Catalyst System Efficiency Below Threshold (Bank 1). What is the MOST accurate interpretation of this code?
- The upstream oxygen sensor has failed
- The catalytic converter is not reducing tailpipe emissions efficiently enough (Correct answer)
- There is a rich fuel condition upstream of the converter
- The downstream oxygen sensor signal is too high
Correct answer: The catalytic converter is not reducing tailpipe emissions efficiently enough
P0420 is set by the ECM when it detects that the downstream (post-cat) oxygen sensor is producing a signal too similar to the upstream sensor, indicating the catalytic converter is no longer storing and releasing oxygen efficiently. The code points to converter inefficiency, though upstream issues (exhaust leaks, rich conditions) must be ruled out before replacing the converter.
ASE - Automotive Service Excellence Practice Test #2 1
A technician is diagnosing a no-start condition on a gasoline engine.
The engine cranks normally but will not fire.
Spark is confirmed at all cylinders.
What should be tested NEXT?