Back in the old days, before the government required cars to have uniform diagnostic jacks and protocols, we used to figure out what was wrong with our cars by moving the ignition key back and forth and counting how often the "check engine" light blinked. Then, we'd look it up on the Web or, if we had one, in the factory service manual.
Then they started coming out with handheld and computer-based scanners. I remember wishing they had something I could bring to the car, grab codes with, then plug into my computer and read. It's a bit of a pain to drag a computer out to the car and hook up the interface box with all the various cables and run special software, just to see if you have an error code. It didn't help that all these programs tended to be Windows only, so I either had to drag by Windows laptop with no battery life or run Windows under Parallels Workstation on my Mac. And even when I was done, I saw the codes, but no details on what they might mean; some are self explanatory but others are not.
Software of this type often seems to get superceded by newer programs; updates and upgrades are not certain, even for web services. Don't rely on regular updates.
Into the breach comes CarMD, a code scanner with a difference. The scanner itself is small and portable, self-powered by replaceable AA batteries (rechargeables work well), and hooked into software. You can read the numeric codes on the scanner once it's been plugged in, and when you put it into your computer via the USB port, the company's software will tell you what they mean and provide diagnostic information and even cost estimates based on your particular car. There are no cables to deal with.
The CarMD works seamlessly, for the most part. The device reads the car's data in around three to ten seconds, and beeps when it's done; green and red lights show its findings quickly, and the screen, as we mentioned, shows the actual error codes. (You can use it without the company's software, just to read codes.)
Unlike most competitors, CarMD has software for the Mac and Linux, as well as Windows, although their task was simplified by the nature of the system. All the software does is hook the device up to their web site, which then does the heavy lifting. There's nothing wrong with that. It did work well on our laptop, with no particular issues other than adding an icon to the Dock each and every time it started. That means that, if you agree to let it auto launch on startup (the default), your Dock will soon be littered with little round highway logos that you have to trash. The alternative is just leaving one icon in the dock, not letting it auto load, and remembering to run the software before plugging the device into your laptop.
CarMD does have limitations, the chief one being that, because of its simplicity, it can't be used as a "copilot" device to test sensors and find problems on the fly, while you drive or fiddle with things; it only tells you what the computer said, and what the company's experts think it means. You also can't erase the codes stored in your computer, which would be handy for making sure your fix worked. (It does provide a snapshot of your car when the problem occurred, which is taken from the car's computer, and can be very helpful indeed.) Finally, the system only shows the universal codes that apply to all vehicles, which is a common shortcoming in this kind of device; though we understand Actron is selling a scanner now that provides automakers' proprietary codes, the cost is somewhat higher, with listings between $230 and $345 on the Web. CarMD, on the other hand, sells for $99.
The online system will provide you with full text of service bulletins (it automatically lists them for you) for $20 a year, and provides the text of recalls without cost or an extra membership.
Overall, we liked the price and ease of use of the CarMD, which made it far easier to work with than the more comprehensive solutions we've tried in the past. As long as you don't encounter proprietary codes, which are less common than the generic ones, and as long as you don't need to reset codes or get a realtime analysis of your system, it does the job well. For the latter capabilities, you may want to spend a bit extra on the Actron (at two or three times the price); the computer-based systems we tested provide real time displays of sensor data and can clear codes, but don't list proprietary codes either, cost more, and are clunkier to operate when all you want is an explanation of what's gone wrong.
See our review of computer-based competitors, Palmer's PCMScan and AutoTap.
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