It’s not just AutoZone that offers free OBD2 reading, most auto parts places do. They all do it for the same reason, and most of them use it as leverage to try to get you to spend money. I gave you this for free, you should be grateful and buy something. Please try to keep in mind that they are a place of business. If they don’t sell stuff, they go out of business and there goes our free OBD2 check. The folks at AutoZone want to get you into their store in hopes that you will buy stuff. That’s how they make their money. The same goes for Wal-Mart, Dairy Queen, CVS, 7-Eleven, and any other place of business. It doesn’t take a rocket scientist to realize that not everyone at the local auto parts store is an experienced mechanic. In fact, most of them are not. Regardless of background, it is still their jobs to sell you stuff. That’s how stores stay in business, they sell stuff. Most Auto Zones can print out a little ticket with the codes they read from your car so that you can take it to a mechanic to get the necessary repairs done. Yes, they are pushed very hard by the management to sell you stuff based on what that little ticket says. They are a business that sells things. If it’s a misfire, they will have an injector cleaner that just happens to be on sale. Usually, a misfire is caused by a faulty ignition coil or spark plug, but a clogged injector will give the same code, and a jug of Techron is not especially expensive. If it’s a vacuum leak, they have gas caps. The thing that not one answer I’ve seen so far ventures to mention is that sometimes, that spark plug, or ignition coil, or gas cap, or injector cleaner is the solution. When I worked there, I always told my customers the same thing, “Before you start throwing money at this problem, check these things out yourself or take it to a mechanic.” …and I would show them the list of possible solutions on the little ticket, which are usually pretty easy to figure out if you’re a functioning adult. Yes, it is somewhat of a sales catch, but you don’t have to buy anything. Most of the people at AutoZone are just folks like you and me who are just trying to earn a living. It is a sad state of affairs that they are pushed VERY hard to get their customers to buy things before getting good information. I was pushed like crazy to sell anything and everything when a code came up on someone’s car. Instead, I kept hanging on one of Auto Zone’s marketing slogans about “trustworthy advice,” which I tried to give. Didn’t make the boss happy, but I slept comfortably at night. Contrary to contemporary philosophy, it is not evil to try to be profitable, it’s good sense. It is evil to use misleading information to achieve that goal, so think it through before you spend money. I will say this, getting the freebee and walking away is a lot like using a store’s bathroom and walking out without buying anything; it’s the act of a very tacky ingrate.