Will AutoZone Check My Engine Light for Free?

We chase a lot of check engine lights in Metro Detroit. Plenty of them start the same way. Somebody got a free scan at a parts store, bought the part on the printout, put it in, and the light came back. So yes, go get the free scan. It is a good first step. Here is how to use it so it does not cost you a part you never needed.

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About 8 min read

What You Get at AutoZone for Free

AutoZone calls it Fix Finder. Its Fix Finder page, read on October 11, 2026, says every one of its more than 6,200 US stores offers it during business hours. It reads the check engine, ABS and maintenance lights. The test often takes less than a minute once the reader is plugged in. You get a printed copy and an emailed copy, and the store can reprint a report from the last 30 days.

On some cars the report also shows emission readiness, oil life, brake pad life, battery voltage and tire pressure data. AutoZone notes that some of those items are not available on every vehicle. It cannot be done online. The reader has to plug into the car, so you go to the store.

You can also do it yourself in the lot. AutoZone's self serve guide says you borrow the reader from the counter, plug it into the port under the dash, and turn the key on without starting the engine. The screen goes from read to done in about 4 to 5 seconds. Then you bring the reader back inside. It only talks to AutoZone's own counter terminal, which prints the report.

The other big chains do this too. Here is how they compare.

Where	What it costs
AutoZone Fix FinderEvery US store, business hours, printed and emailed report	Free
O'Reilly VeriScanAny 1996 or newer passenger vehicle, per O'Reilly	Free
Advance Auto PartsFree code scans on most OBD2 cars, per Motor1	Free
Supercanic Detroit diagnosticOur posted price, at your driveway, counts as the first hour if we fix it that visit	$150 call out
Supercanic Detroit smoke testOur posted price, for leaks no scanner can see	$225

What the Free Scan Cannot Tell You

This is the part the printout does not say out loud. A trouble code tells you which system the computer flagged. It does not tell you why.

Take a lean code like P0171. It says the engine is getting too much air for the fuel. That could be a torn intake boot, a vacuum leak, a weak fuel pump or a dirty sensor. Motor1's August 24, 2026 piece makes the same point with a misfire code. It could be a worn spark plug, a bad coil, a fuel injector, a vacuum leak or something worse. Buy the first part on the list and you may just be guessing with your own money.

Remember who is reading the code for you, too. The scan is free because you are standing in a store that sells the parts on the report. Motor1 says it plainly. There is nothing wrong with that. You just do not have to buy anything. Take the report home and use it.

Two more cases the free scan handles badly.

• The light is on but no code shows up. AutoZone's own guide says this can mean a maker specific problem the basic reader cannot see, and it may need to be handled at a dealer.
• The light went off on its own. That is often normal. The EPA's fact sheet on onboard diagnostics says the computer turns the light off by itself after it checks a system three times in a row and the problem is gone. A loose gas cap is the classic one. Tighten it and the light should go out within a few days.

Read the Three Lights on the Scanner

The AutoZone reader has three small lights under its screen. Its self serve guide explains them.

Light	What it means
Green check markAll systems report okay	No codes
Yellow question markSome self tests are not finished, or a code is pending	Drive and scan again
Red XOne or more trouble codes are stored	Get the report

The yellow light matters if you are buying a used car. When we do a used car inspection, a not ready result is a question for the seller. Ask when the codes were last cleared and when the battery was last changed. A car that just had its codes wiped can look clean on a quick scan.

Flashing Light? Skip the Parts Store

A steady light means get it looked at soon. A flashing light is different. The EPA fact sheet says a blinking light means a fairly severe misfire. It says to slow down and get service as soon as you can, because a bad misfire can damage the catalytic converter fast, and that is usually the most expensive emission part to replace.

So if the light is flashing, or the car is shaking, losing power or running hot, do not drive across Detroit on I-94 for a free scan. Get it to a mechanic or have one come to you.

Michigan Has No Emissions Test, So Nobody Makes You Fix It

Michigan has no emissions test for your car. A 2010 Capital News Service report quoted a state spokesman saying Southeast Michigan had a testing program until the mid to late 1990s. It ended when the state met the federal ozone standard. The same report said Ohio, Indiana, Wisconsin and Illinois had counties that did require the test.

That is why we see cars in Wayne, Oakland and Macomb counties that have had the light on for a year. Nothing forces the fix. But the EPA fact sheet gives the reason to fix it anyway. A worn spark plug can cause a misfire you barely feel. Left alone, that misfire can ruin the catalytic converter. Then a cheap plug job turns into a plug job plus a converter.

Check the Free Warranty Before You Pay Anyone

This is the money tip almost nobody mentions. The same EPA fact sheet says federal law requires the emission control systems on 1995 and newer cars to be warranted for 2 years or 24,000 miles. The engine computer and the catalytic converter must be warranted for 8 years or 80,000 miles. Many makers go further.

So if the free scan points at the converter or the engine computer, and your car is under 8 years and 80,000 miles, call the dealer before you pay anyone. Check your warranty booklet for the exact terms on your car.

Free Scan, Then What

1. Get the free scan. Write down every code, not just the first one. Keep the report.
2. Try the easy fix first. If the report points at the gas cap or an evaporative leak, tighten the cap and drive a few days, as the EPA suggests.
3. Check the warranty. Converter or engine computer on a car under 8 years and 80,000 miles? Call the dealer.
4. Test before you buy. If the light stays on, get the circuit tested. In Michigan the shop has to give you a written estimate before it starts, under section 257.1332 of the Motor Vehicle Service and Repair Act. Ask whether the diagnostic fee counts toward the repair.

For the price side, our post on whether $150 an hour is expensive lays out what Michigan shops charge in 2026.

How We Handle a Check Engine Light in Detroit

Bring your free AutoZone report. We are happy to start from it. Our check engine diagnostic is part of a flat $150 call out to your driveway, and it counts as the first hour if we do the repair on that visit. Leaks that no scanner can see get a $225 smoke test. You get the codes, the readings and what we ruled out in writing, and a written quote before any part is bought. Our full price list is posted.