ASVAB Auto & Shop Information Study Guide
Updated July 2026 · AFQT · 7 min read
The ASVAB Auto & Shop Information (AS) subtest measures your practical knowledge of automobiles, engines, hand and power tools, and workshop safety. It is not part of your AFQT enlistment score, but it feeds the mechanical and technical line scores that qualify you for jobs like mechanic, heavy-equipment operator, and construction specialist. Most questions simply ask what a part or tool does, so you can raise your score by learning the purpose of each system rather than memorizing specifications. This guide breaks down every core topic with examples and gives you a proven method to prepare.
What Auto & Shop Information Tests
AS combines two related areas: Auto Information (how a car works) and Shop Information (tools, materials, and safe workshop practice). On the CAT-ASVAB these appear as two short sections of about 10 to 11 questions each; on the paper test they merge into one 25-question subtest. Because AS is not an AFQT subtest, it will not decide whether you can enlist, but a strong score widens the list of hands-on careers you qualify for. To see exactly how it feeds branch composites, read how ASVAB scoring works.
The best news for test day: if you have ever changed oil, used a socket wrench, or watched a repair video, you already know a lot of the answers.
Automotive Systems You Must Know
| System | What it does | Key parts to know |
|---|---|---|
| Engine | Converts fuel into motion | Pistons, cylinders, crankshaft, valves |
| Ignition | Creates the spark that fires the fuel | Spark plugs, ignition coil, distributor |
| Fuel | Delivers fuel and air to the engine | Fuel injector, fuel pump, air filter |
| Cooling | Prevents the engine from overheating | Radiator, water pump, thermostat, coolant |
| Lubrication | Reduces friction between moving parts | Oil pump, oil filter, motor oil |
| Brakes | Slows and stops the vehicle | Rotors, calipers, pads, brake fluid |
| Exhaust | Removes and cleans burned gases | Muffler, catalytic converter, exhaust manifold |
Engine and the four-stroke cycle
Most car engines are four-stroke internal combustion engines. The four strokes are intake (air and fuel enter), compression (the piston squeezes the mixture), power (the spark ignites it and pushes the piston down), and exhaust (burned gases leave). Remember them with “suck, squeeze, bang, blow.” The pistons move inside cylinders and turn the crankshaft, which ultimately drives the wheels.
Ignition system
The ignition system delivers the spark that ignites the fuel-air mixture. The ignition coil boosts battery voltage, and the spark plug fires it inside each cylinder at exactly the right moment. Fouled or worn spark plugs are a classic cause of rough idling and misfires, a common AS question.
Cooling and lubrication
The cooling system keeps the engine from overheating. The water pump circulates coolant, the thermostat regulates temperature, and the radiator releases heat to the air. Separately, the lubrication system pumps oil through the engine so metal parts do not grind, and the oil filter traps debris.
Brakes
Modern cars use disc brakes, where a hydraulic caliper squeezes pads against a spinning rotor to create friction. Brake fluid transfers the force from your foot to the calipers. A spongy brake pedal often means air or low fluid in the lines.
Shop Tools, Fasteners, and Safety
Shop Information asks you to identify tools and know their correct use.
- Cutting tools: A hacksaw cuts metal, a chisel shaves wood or metal, and tin snips cut sheet metal.
- Fastening tools: Use a socket or combination wrench for bolts, an Allen (hex) wrench for hex-socket screws, and the right screwdriver, Phillips or flathead, for the matching screw head.
- Striking tools: A ball-peen hammer shapes metal, while a claw hammer drives and pulls nails.
- Measuring tools: A micrometer and caliper measure small precise distances; a level checks that a surface is flat.
- Power tools: Know the difference between a circular saw (straight cuts) and a jigsaw (curved cuts), plus routers, lathes, and drills.
Fasteners
Fasteners hold parts together. Bolts pass through parts and thread into a nut, screws cut their own thread into material, washers spread the load and protect the surface, and rivets permanently join metal sheets. Knowing which fastener is removable versus permanent is a frequent test point.
Shop safety
Expect a few safety questions. Always wear eye protection when grinding or cutting, keep guards on power tools, unplug tools before changing blades, and clear the workspace of clutter. Safety answers are usually common sense, so read the question carefully.
Top Strategies to Raise Your AS Score
- Learn the job, not the jargon. For every part, ask “what does this do?” Understanding the purpose lets you reason out unfamiliar questions.
- Group parts by system. Studying the whole cooling or braking system together is far easier than memorizing isolated words.
- Use pictures and real cars. Look under a hood or watch short repair clips so the terms attach to real objects.
- Match tools to tasks. Drill which tool cuts metal, drives a bolt, or measures thickness, since that is exactly how questions are framed.
- Eliminate wrong answers. Even a rough idea of a system lets you rule out two choices and improve your odds.
- Do not overthink safety. The safest, most cautious option is almost always correct.
How to Practice
Reading is a start, but you lock in AS knowledge by answering questions under time pressure. Work timed sets on the Auto & Shop Information practice test, then read the explanation for every item, even the ones you got right. Pair it with the Mechanical Comprehension study guide since the two subtests share hands-on reasoning, and follow the full ASVAB study guide to plan the rest of your prep. Steady practice on these core systems and tools is the surest way to a strong AS score and the technical job you want.
