^^ autozone will also use the same computer for FREE on your car to find out what your CEL is about.
a real autoshop will tell you autozone's version is a 'mickey mouse' version..and to some extent they are correct. it won't catch EVERYTHING (such as your toyota dealers 'cart' they have to push out it's so big)..but it will catch 95% of everything and will catch all of the most common problems.
definately worth it to check them out and get them to do that for you. even if it doesnt catch all your specific problems the least it can do is tell you most of the problems (if more than 1 problem occurs) and you can fix that yourself and save some big money. if your CEL stays off, then all's well. if you reset your CEL though and it still wants to come on after doing the work..then there might be an extra problem the 'mickey mouse' version didn't catch...THEN bring it to a dealer or whatnot.
in my experience though, every car we have bought to autozone and my friends have bought to autozone have caught EVERY single thing and we were able to fix it without having to spend about $90 (going rate over here to use a dealers computer) just to see what the problem was.