2024 Edition

ASE A9 Practice Test

ASE identifies Light Vehicle Diesel Engines as an individual service area (A9). The light vehicle diesel engine area involves the following diagnosis components:

• Cylinder Head and Valve Train
• Engine Block
• Lubrication and Cooling Systems
• Air Induction and Exhaust Systems
• Fuel Systems

Tests.com's ASE A9 Practice Test was written by Dr. John Kershaw, an ASE test prep expert: ASE test question developer; ASE Certified Master Technician; ASE Master Truck Technician; and Auto Industry Technical Instructor.  Dr. Kershaw was among the first to receive ASE certification in 1972.  

For the complete practice test, flash cards, exam review and testing tips, check out Tests.com's ASE A9 practice test kit with 130 questions.

General Diagnosis


Which diagnostic tool connects to the Data Link Connector and allows the technician to read light duty diesel engine diagnostic trouble codes?


An orange colored liquid is found under the front of the engine, which of the following fluids is leaking?

Cylinder Head and Valve Train Diagnosis and Repair


Two technicians are discussing engine valve seals. Technician A says to apply a light coat of engine oil to new oil seals and push them in. Technician B says you can install the intake oil seal into the exhaust side or install the exhaust oil seal into the intake side because they are interchangeable. Who is right?


Valve adjustment is necessary following the replacement of a:

Engine Block Diagnosis and Repair


After cleaning a diesel block and crankshaft, what chemical should they be sprayed with?

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When measuring a cylinder for taper wear, which of the following is the MOST likely place for wear?

Lubrication and Cooling Systems Diagnosis and Repair


Technician A says a weak solution of antifreeze may cause corrosion build-up in the cooling system. Technician B says engine coolants and rust inhibitors last the lifetime of the diesel engine. Who is right?


This question has the word EXCEPT. For this question, look for the choice that would NOT fit the described situation. Read the entire question carefully before choosing your answer.

All of the following will happen when an oil filter becomes clogged, EXCEPT:

Air Induction and Exhaust Systems Diagnosis and Repair


A light duty diesel engine has a sever oil leak at the rocker cover. The technician has replaced the rocker cover gasket but the gasket still leaks. Which of the following is the MOST likely cause?


A Catalyzed DPF (Diesel Particulate Filter) requires oil with which of the following characteristics?

Fuel Systems Diagnosis and Repair


A diesel engine with an electronically managed solenoid pump and nozzles has an active diagnostic trouble code for a single cylinder #3 misfire with a rough idle at operating temperature. Which of the following actions could cause the problem?


The primary fuel system supply side vacuum test should be performed at which area:

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Written by:
Dr. John Kershaw
ASE Test Prep Expert

ASE Test Question Developer

ASE Certified Master Technician

ASE Master Truck Technician

Auto Industry Technical Instructor

Among first ASE Certified in 1972
Actual ASE A6 Topics

• General Electric/Electronic 
• Battery and Starting Systems
• Charging Systems
• Lighting Systems
• Instrument Cluster/ Driver Info.
• Body Electrical Systems 


Number of Questions on the Actual ASE A Series Tests

A1 – Engine Repair (60)
A2 – Automatic Transmission/Transaxle (60)
A3 – Manual Drive Train & Axles (50)
A4 – Suspension & Steering (50)
A5 – Brakes (55)
A6 – Electrical/Electronic Systems (60)
A7 – Heating & Air Conditioning (60)
A8 – Engine Performance (60)
A9 – Light Vehicle Diesel Engines (60)