ASE A9 Light Vehicle Diesel practice test
The A9 test covers diesel engines in pickups and light trucks: high-pressure common rail fuel systems, turbocharging, cold-start hardware, and the modern aftertreatment stack (DPF, EGR, SCR/DEF). Optional for Master status — valuable for anyone working on diesel pickups.
A diesel has low power with no smoke, and boost pressure is below normal. Exhaust backpressure measured ahead of the aftertreatment system is far above specification at load. Which is the MOST likely cause?
How the A9 test works
50 scored questions
+ ~10 unscored research questions
75 minutes
computer-based, at a test center
$62 per test
plus one $34 registration fee per order
Valid 5 years
then a shorter recertification test
ASE does not publish one universal passing percentage; the passing standard is set by test. TorquePrep uses 80% as a conservative practice target, not as an official ASE cut score. The certificate is issued once ASE verifies your required work experience.
What the A9 test covers
The official task list for A9 Light Vehicle Diesel Engines breaks down into these content areas — the practice bank above draws from all of them:
- General diesel engine diagnosis — hard start, smoke color, compression, noise
- Cylinder head, valve train, and engine block service
- Lubrication and cooling systems
- Air induction and exhaust — turbochargers, charge air coolers, restrictions
- Fuel system — high-pressure common rail, injectors, low-pressure supply, water in fuel
- Emissions and aftertreatment — EGR, DPF regeneration, SCR/DEF
Frequently asked
- How many questions are on the ASE A9 test?
- The A9 test has 50 scored questions plus about 10 unscored research questions, with a 75-minute time limit.
- Is A9 required for Master Automobile Technician status?
- No — Master status requires A1 through A8. A9 is an additional credential for light-vehicle diesel work.
- How does A9 differ from the T2 diesel test?
- A9 targets diesels in cars and light trucks (pickup-class common rail engines); T2 covers medium and heavy truck diesel engines. The fundamentals overlap, but the platforms and systems differ.
Exam length, timing, fees, and content areas checked September 11, 2026 against the official ASE test table and ASE study guides.