ASE A9 Light Vehicle Diesel Engines Certification Test Exam Guide

The A9 knowledge test is organized into content areas that weight diesel-specific diagnosis and repair skills differently. Two of the larger areas cover systems technicians handle daily on diesel-powered vehicles:

• General Diagnosis — 9 questions, 18% of the test
• Air Induction and Exhaust Systems Diagnosis and Repair — 12 questions, 24% of the test
• Fuel System Diagnosis and Repair — 13 questions, 26% of the test

Every ASE certification test, including A9, also mixes in 10 unscored research questions alongside the scored content. These questions aren't labeled, so test-takers answer the full set without knowing which ones count toward the final score.

Taking the ASE A9 test costs $62 per test, plus a separate $34 registration fee charged per order. Candidates should check ASE's official fee schedule for the most current pricing before registering, since fees for other tests or bundled orders can differ.

The A9 exam presents 60 total questions in 75 minutes, of which 50 are scored — the other 10 are unscored research questions used to gather performance statistics. ASE doesn't publish a single fixed passing percentage; the passing standard is set through statistical analysis of the scored questions, so candidates should refer to the official ASE Automobile Study Guide for the current passing criteria. Certification earned by passing is valid for five years, and recertification uses a shorter 25-question, 30-minute version of the test.