Some here may not know what Techstream or a scan tool does so here's a quick synopsis:

A scan tool, depending on the model, will allow you to read codes on your car and troubleshoot most of those pesky dashboarrd wanring lights/ "Check engine lights". It plugs allowing you to see most faults and in many cases erase those. Sometimes you can borrow one from an Autozone, for free. Heading to your dealership will usually cost you >$100 for them to spend all of maybe 30 secs to tell you what the codes are and how much they'll bend you over to repair them. These run anywhere from $30 to several hundreds bucks

TechStream - Heard it mentioned here a few times but wasn't sure what it entailed. Techstream is the software Toyota themselves uses for all their dealerships, this allows a much more comprehensive "deep dive" into all your cars computers so you can see codes, erase codes, customize many features of your car, troubleshoot, it suggests fixes, pair a new key to your car, reset airbags or car seats, and lots more. When I purchased mine it comes with the needed cable that plugs into the OBDII port just below and to the left of your steering wheel. Techstream does anything a scan tool does plus much more.

After watching a few Techstream videos on YT I opted to try buying a Techstream cable and software for $25 and was able to get it to run fully on my Windows 64-bit laptop no problem... the results are amazing! Real-time engine data showing anything/everything you'd want including how each fuel injector is functioning. I can now do my own key pairing which the dealer wanted >$200 to do. I have adn had used a scan tool to erase some codes earlier but this software shows me histories of every module, updates, etc. I know many of you here have this and have been running it for sometime now but for newbies or those that are not tech-geeks thought this might help some. As far as actually using this sfotware/cable there are many YT videos showing how to address pretty much everything.

If you're considering buying a used Toyota or Lexus this would be an absolute "must have" as it shows any current issues adn usually the history as well.

Hope this helps someone out there