PrepPass also publishes a complete study guide for this exam as a downloadable book (71 pages, 40 practice questions inside, $14.99).
Test what you know · free, all of it
The same 420 questions, dealt five ways. Pick the one that fits the time you have.
Learn what the questions test
Practice finds the gaps. Reading closes them. The five chapters below are free to read online. The study guide book is a separate download, sold on its own page.
Before you sit
See the questions first
Real items, with the answer marked and the reason written out — the same format as all 420.
An oxygen (O2) sensor in the exhaust provides feedback to the PCM about:
Why: The oxygen sensor measures residual oxygen in the exhaust, telling the PCM whether the mixture is rich or lean so it can adjust fuel trim. A lazy or failed sensor degrades fuel control and emissions. Wide-band sensors report the actual ratio rather than just rich/lean.
Using Ohm's law, a 12-volt circuit with 4 ohms of resistance will carry a current of:
Why: Ohm's law states current equals voltage divided by resistance, so 12 volts divided by 4 ohms equals 3 amps. Understanding this relationship is essential for diagnosing circuit faults. Higher resistance in a circuit reduces current flow for a given voltage.
Watch
The exam itself
| Questions | 120 |
|---|---|
| Sections | Engine Performance (A8) · Electrical (A6) · Brakes (A5) · Suspension & Steering (A4) · Engine Repair (A1) · Transmission & Drivetrain (A2/A3) · Heating & A/C (A7) · General |
| Our bank | 420 questions · updated September 2026Written from National Institute for Automotive Service Excellence (ASE) |
| Languages | English |
| Source | National Institute for Automotive Service Excellence (ASE) |
Helpful resources
Studying for the ASE Automobile Certification (A1–A8) in order? ASE Automobile Certification (A1–A8) — Complete Study Guide (2026) — PDF + EPUB, $14.99 · 14-day refund →
Questions
All 420 questions, the timed mock and the report are free with no sign-up. A free account only adds saving your progress. The study guide book is sold separately, $14.99 one-time; nothing in the practice requires it.
No. Ours is 100 questions in 120 minutes; the real exam is 120 questions. Use the mock for stamina and section timing, not as a score predictor.
Yes. PrepPass sells ASE Automobile Certification (A1–A8) — Complete Study Guide (2026), a PDF + EPUB download, $14.99 one-time; the practice on this page stays free without it. See the study guide →
