I'm always a fan of inexpensive and effective tools. Like the MT87 clamp meter before, this gem of a tool is one that was inexpensive enough that I had to try it out. It's an OBD-II Bluetooth adapter for your car.
In short, OBD-II is an interface to your car's computer. It's been required by law to be available in your car for 1996 and newer gas cars and 2004 and newer diesel cars in the USA. The plug must be within a couple feet of your steering wheel. You get all kinds of information about what's going on through this port. When your check engine light comes on, this is how the mechanic knows why it turned on. Lately Progressive Auto Insurance has been advertising Snapshot, a device that reduces your insurance rates based on how you drive. This also uses OBD-II to see how aggressively you drive. A search for OBD-II on Amazon and you'll find many devices that can plug in to get check-engine-light codes and clear them or act as a trip computer for fuel monitoring, like the ScanGauge-II. Most are expensive or inconvenient for constant monitoring. You'll also find Bluetooth adapters like the one we'll talk about.
One day I saw a post on Slickdeals for a $20 OBD-II code check tool for when your check engine light comes on. In the comments a person said how you can get an ELM327 Bluetooth module for less on eBay. ELM327 is a chip that allows for easy communication with the car's computer through the OBD-II port. There are many knockoffs of this chip on the market, usually directly from China. A Bluetooth version of an ELM327 adapter costs as little as $13 shipped on eBay. These probably use the knockoff chips.
This adapter is no good by itself, though. Bluetooth is a wireless communication protocol so you need another Bluetooth device to pair with it. Almost every cell phone has Bluetooth and probably every Android smartphone does. It's usually used in cell phones for those wireless headsets that, unless you're in a car, make you look... well... ... ... okay so that's Bluetooth.
Torque Pro is a great app by Ian Hawkins for Android smartphones that connects to your OBD-II adapter through Bluetooth. It costs $5 and there's a free limited version available for making sure you don't waste five more dollars after getting an adapter that doesn't work. With it you can get live data from your car about fuel consumption, engine use and performance, and more. It can also check engine codes like those other scan tools. Fun!
Buying stuff from China has its own risks, however. If you ask me, if you bought something off eBay directly from China and it doesn't work, just throw it away. Return something to China? Good luck. I didn't want to take that risk or wait the 2-6 weeks it can sometimes take to get things from there. eBay lets you show only items in the US only. I, however, suspected many of the filtered listings were still direct-from-China users with a trick, US item location, like this one.
I learned that in the listing when you click on the seller's feedback score or number, it will show at their real location. Or at least a more likely true location.
Here is the one I bought. I ended up getting one through the seller "barstore" which is located in the US based on what I showed above, their shipping label, and the delivery speed of just a few business days. If anything didn't work, I feel confident I'd be able to return it without much trouble. I paid about $16 for the device. It's a little smaller than a credit card and maybe an inch thick.
On the back through the blue plastic you can see this. If you do an eBay search for "bluetooth serial", you'll see modules just like this one for as little as $6. The ELM327 speaks serial and your phone speaks Bluetooth. This translates.
There's a lot of info on the Torque app and I won't talk too much about it but say that it really is the reason for buying this adapter. You can use a laptop with Bluetooth to talk to it and can even find USB Bluetooth adapters for as little as $1 shipped. The OBD-II Bluetooth adapter even came with a small CD with software for using it in Windows. All of the software on that CD could also be found on the Internet. But I recommend Torque on Android for three reasons. First, it's much much more convenient than lugging a laptop around. You may think a laptop in a car is okay but it's not. It's a pain. Second, Torque is much better than most of the software you'll find for laptops until its price is on another planet. Even if you don't have an Android phone, you could get a cheap, used phone just for this purpose and still come out ahead. Third, almost every Android smartphone also has GPS. Torque will also collect GPS info and it's nice to have both in one place.
Some downsides for this device include: slower than Scantool.net's $200 adapter, knockoffs don't support the original manufacturer (Elm Electronics), knockoffs can be error prone with time (we'll see how mine does but so far so good), requires an Android phone, and you might not be able to use this if you use Snapshot from Progressive.
I bought this to be able to monitor fuel economy live. My Yaris also doesn't have a tachometer or temperature gauge so that's available now, too. And if that check engine light comes on, I can see what it means, too. Not considering the phone, I spent $21 total. I had always wanted a ScanGauge-II but those are $160. This is much better for the money, if you ask me. And $21 is a pretty low price to have my car's peformance...