ASE - Automotive Service Excellence Practice Test #4 1

Question 1

A technician is performing a compression test on a 4-cylinder engine. Cylinders 2 and 3 both show low compression readings. What is the MOST likely cause?

Accepted Answer

A blown head gasket between cylinders 2 and 3

Answer

Adjacent cylinders with simultaneous low compression strongly indicate a blown head gasket between those cylinders, allowing combustion pressure to leak between them. Worn rings would typically show improvement with a wet compression test, and valve problems rarely affect two adjacent cylinders simultaneously in the same pattern.

Question 2

A customer complains of a vibration felt in the steering wheel only during braking. The vibration is not present during normal driving. Technician A says the front brake rotors are likely warped. Technician B says the front wheel bearings are worn. Who is correct?

Accepted Answer

Technician A only

Answer

Steering wheel vibration that occurs only during braking is a classic symptom of warped or thickness-variation front rotors. Warped rotors cause pedal pulsation and steering shake specifically under braking force. Worn wheel bearings typically produce noise and vibration during driving or cornering, not exclusively during braking.

Question 3

A vehicle's OBD-II system sets a P0420 code (Catalyst System Efficiency Below Threshold, Bank 1). Before condemning the catalytic converter, what should the technician inspect FIRST?

Accepted Answer

Exhaust leaks upstream of the downstream oxygen sensor

Answer

An exhaust leak upstream of the downstream (post-cat) oxygen sensor can introduce outside air, causing the sensor to read falsely lean and mimicking a failing catalyst. This is a common misdiagnosis trigger and should be eliminated before replacing an expensive catalytic converter. The downstream O2 sensor's readings depend entirely on exhaust gas composition reaching it.

Question 4

When measuring battery state of charge with a hydrometer on a conventional flooded lead-acid battery, a technician finds one cell reads 1.175 specific gravity while the remaining five cells read approximately 1.265. What does this indicate?

Accepted Answer

One cell has a dead short or internal failure

Answer

A single cell reading significantly lower (more than 0.050) than the others indicates that cell has an internal short circuit or plate failure and cannot hold a charge. A battery with one dead cell will fail under load even if the other cells appear healthy, and the battery must be replaced. A low charge condition would affect all cells relatively equally.

Question 5

A technician is diagnosing a vehicle with a complaint of hard starting when the engine is hot, but normal starting when cold. The engine cranks normally. What is the MOST likely cause?

Accepted Answer

Fuel pressure dropping due to a leaking fuel pressure regulator or injectors (hot soak)

Answer

Hot soak hard starting is a classic symptom of fuel pressure bleed-down after shutdown. A leaking fuel pressure regulator or injectors allow fuel rail pressure to drop while the engine is off and hot. When restarted, the engine must crank longer to rebuild pressure before fuel can atomize properly. Cold starts are unaffected because pressure holds during the overnight soak.

ASE Practice Test

ASE Practice Test

ASE - Automotive Service Excellence Practice Test #4 1