ASE S2 Diesel Engines (School Bus) Practice Questions - ASE S2 - Diesel Engines (School Bus) Certification Exam - ASE S2 Diesel Engines (School Bus) Practice Questions - ASE S2 - Diesel Engines (School Bus) Certification Exam

Question 1

A school bus with a Cummins ISB diesel engine cranks normally but will not start, and the technician confirms there is no fuel reaching the high-pressure pump. Which check should be performed FIRST?

Replace the high-pressure common-rail pump Replace all fuel injectors as a set Increase the rail pressure relief valve setting Inspect the low-pressure (lift/transfer) supply circuit and primary fuel filter for restriction

Correct Answer:

Inspect the low-pressure (lift/transfer) supply circuit and primary fuel filter for restriction

Question 2

Technician A says low engine compression on one cylinder can cause hard starting and a miss. Technician B says a cylinder cutout (power balance) test can help isolate a weak cylinder on an electronically controlled diesel. Who is correct?

Technician A only Technician B only Both A and B Neither A nor B

Correct Answer:

Both A and B

Question 3

A school bus diesel produces excessive black smoke under acceleration but idles cleanly. The MOST likely cause is:

Coolant entering the combustion chamber Worn valve stem seals A failed cabin heater core Insufficient air for the fuel being delivered (over-fueling/low boost)

Correct Answer:

Insufficient air for the fuel being delivered (over-fueling/low boost)

Question 4

During a cylinder compression test on a school bus diesel, one cylinder reads significantly lower than the others. Adding a small amount of oil through the injector bore raises that cylinder's reading noticeably. This indicates:

A burned valve or damaged valve seat A cracked cylinder head between cylinders A leaking head gasket to the cooling jacket Worn rings or cylinder bore (ring sealing issue)

Correct Answer:

Worn rings or cylinder bore (ring sealing issue)

Question 5

A school bus engine has low power and the ECM logs no active fault codes. The technician should:

Immediately replace the ECM Perform a systematic test of air, fuel, and exhaust restriction along with rail pressure and boost data Disconnect the EGR valve and road test Add fuel system cleaner and return the bus to service

Correct Answer:

Perform a systematic test of air, fuel, and exhaust restriction along with rail pressure and boost data

Exam overview

About this Exam

Prepare with the ASE S2 Diesel Engines (School Bus) Practice Questions - ASE S2 - Diesel Engines (School Bus) Certification Exam practice quiz. This question bank includes 100 questions covering diesel, school, technician, engine, and cause. Use it to review important concepts, identify knowledge gaps, and build confidence for the related exam, course, or assessment.

More details

Additional Information

ASE S2 Diesel Engines (School Bus) Practice Questions - ASE S2 - Diesel Engines (School Bus) Certification Exam

This practice set contains 100 questions from the matching question bank and focuses on diesel, school, technician, engine, and cause. Work through each question carefully, review the provided solutions, and revisit topics that need more study before your next attempt.

This is an independent study resource intended for practice and review; it is not an official examination or an endorsement by any organization named in the title.

Quiz information

Frequently Asked Questions

The complete question count is available after full access is unlocked.

No fixed duration is currently configured for this quiz.

Question explanations are included where they are available in the quiz content, helping you review the reasoning after answering.

Yes. You can retake the practice test again as you continue studying during your available access period.

After your access is confirmed, you can continue into the complete practice exam from this quiz flow.

Unless explicitly stated otherwise, this page provides independent practice material for study and exam preparation and is not the official examination itself.

Correct Answer:

Correct Answer:

Correct Answer:

Correct Answer:

Correct Answer:

About this Exam

Additional Information

ASE S2 Diesel Engines (School Bus) Practice Questions - ASE S2 - Diesel Engines (School Bus) Certification Exam

Frequently Asked Questions

Related Questions

2026 FFM Agent Broker Certification Practice Exam

3CX Academy Advanced Certification Practice Exam

3CX Academy Basic Certification Practice Exam

3CX Intermediate Certification Practice Exam

Ultimate Study Guide for the Argus Certification Practice Test

Arizona Caregiver Certification Practice Exam