Only problem with Autozone just reading the code is that's all you get is a code. You still have to determine the cause of the code. Remember, if you get something like an o2 code, chances are it's not the o2 sensor, for example. You still need to monitor the inputs and outputs and compare them to reference parameters. I've seen way too many times at work, someones gone to Autozone and had the codes read, then sell them the parts those "experts" said it needs. They come to us for installation, and being a professional want to know WHY these parts were sold to them. So, you get the code(s), do a diag and discover that none of the $350 of parts from Autozone are needed. The problem is something totally different. So, yes they will read the codes for you, just don't commit to any parts until you are sure they will fix the problem. Just because you get a TPS code doesn't automatically mean the TPS is bad. Could be a wire, connector, PCM, or a sticking/worn throttle shaft, or possibly some other seemingly unrelated problem that makes the PCM "think" there's a TPS problem. Of course it could be the sensor itself also. As I've said before, this is the reason it's so expensive to take your truck to a shop, and I mean a good shop where they know what they're doing, are honest and care about their work. Autozone doesn't qualify on for any of those.