2023 Edition

ASE L2 Practice Test

ASE identifies Electronic Diesel Engine Diagnosis Specialist as an individual service area (L2). The electronic diesel engine diagnosis area involves the following components:

• General Inspection and Diagnosis
• Electronic Engine Controls Diagnosis
• Air Exhaust Systems Diagnosis
• Fuel Systems Diagnosis
• Emission Systems Diagnosis

This free sample ASE L2 Practice Test below consists of 8 questions organized within 4 sections.
Tests.com's ASE L2 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 Complete 100 Question L2 Practice Test, a 100 question practice test kit for the ASE L2 Exam.

General Inspection and Diagnosis


A diesel truck equipped with a JWAC (Jacket Water Aftercooler) has low power under load. Which of the following could be the cause?


A medium duty truck using a HEUI (hydraulically actuated electronically controlled unit injector) fuel system has a misfire code when hot.  Technician A says worn HEUI injectors could be the cause.  Technician B says a shorted glow plug could be the cause.  Who is right?

Electronic Engine Controls Diagnosis


The technician gets an infinite ohms reading on the ohmmeter function of the DMM (Digital Multimeter), when measuring resistance in a circuit.  Which of the following could be the cause?


Technician A says you do not have to solder a repaired wire. Technician B says wire insulation damage is sometimes found where the wire passes through an opening in a metal part.  Who is right?

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Air Exhaust Systems Diagnosis


Which of the following measuring tools is MOST likely used to measure the temperature of the diesel exhaust gases?


An active diagnostic trouble code is found on a heavy duty diesel engine with VVT (Variable Valve Timing).  Technician A says the camshaft actuator is opening the exhaust valve too early.  Technician B says a slow response could cause the engine not to meet exhaust emissions.  Who is right?

Fuel Systems Diagnosis


The engine cranks on a diesel, but will not start. During diagnosis, the ECM (Electronic Control Module) will not communicate with the diagnostic tool. What is the MOST LIKELY cause?


Technician A says the diesel plastic fuel lines are separated by removing a clip and disconnecting (squeezing) the secondary latch on the line fitting.  Technician B says an air leak at the line connecting the tank pick-up to the transfer pump can cause low-power and hard starting.   Who is right?

Emission Systems Diagnosis

9. Which of the following tools best measures backpressure restrictions?
10. The EGR (Exhaust Gas Recirculation) system is disabled under what engine conditions?

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Quality starts with who wrote the material.
Our practice exam writer
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)