ASE Advanced Level Tests: L1, L2 and L4

How advanced tests differ

Advanced-level tests are longer, cost twice as much as standard tests, and test diagnosis more than repair. ASE positions them for technicians who already hold the core credentials and want to prove depth in a specific area.

They are not a replacement for the Master set. Most have prerequisites that point back to it, so the core tests come first.

L1: advanced engine performance

ASE describes L1 as covering diagnosis of general power-train, computerized power-train controls including OBD II, ignition systems, fuel and air induction, emission control systems and inspection and maintenance test failures. It is the top-end drivability test.

You must have passed A8 first. The recertification version, L1R, is the longest recertification test in this group, with 50 questions and 2 hours 15 minutes.

L2: electronic diesel engine diagnosis

L2 covers general diesel engine diagnosis, electronic engine controls, air induction and exhaust systems, diesel fuel systems, and specific fuel systems such as high pressure common rail, electronic unit injector and hydraulic electronic unit injector.

Its prerequisites cross series: ASE accepts diesel engine tests from the automobile, transit bus, school bus and truck series, plus a matching electrical test. A light vehicle diesel technician with A9 and A6 qualifies as readily as a truck technician with T2 and T6.

L4: driver-assistance systems

L4 is the newest-style credential in the group. ASE describes it as focusing on the diagnosis, service and calibration of radar, camera, ultrasonic and other advanced driver assistance systems. It has no prerequisite test but asks for 3 years of relevant hands-on experience, or an approved mix of training and experience.

ADAS work is growing in both collision and mechanical shops because windshield, bumper and alignment jobs can all require sensor calibration. Where it applies to you depends on the work your shop does.

• ▸Technicians who do drivability work should start with A8, then L1.
• ▸Diesel specialists can combine T2 or A9 with an electrical test to reach L2.
• ▸Collision and alignment technicians may look at L4 for calibration work.

Choosing between L1, L2 and L4

These tests are slower going than standard exams. L1 allows 2 hours 30 minutes for 50 scored questions, about 3.0 minutes each, and L2 allows 2 hours for 45, about 2.7. Standard tests allow roughly 1.7 minutes a question, so the advanced questions are longer and more involved.

Cost is also a factor. A single advanced test is $158 with the registration fee, before sales tax where it applies. That is our own sum from ASE's published fees.

The best choice is the one that matches the work you do. A drivability specialist gets the most from L1, a diesel diagnostician from L2, and a technician who calibrates sensors from L4. If none of these fits your current work, the core series is probably the better place to spend your time and money first.

ASE Advanced Level (L1, L2, L4): common questions

Where these facts come from

Test lengths, rules and fees are taken from the ASE pages listed under Sources and were checked on October 20, 2026. ASE can change them at any time, so confirm on ase.com before you register. ASE certification is a credential from a nonprofit, not a government license. AutoHire is not affiliated with ASE. Calculated totals, where shown, are AutoHire sums of ASE's published fees.

Data as of October 20, 2026.

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