Tech Tip Guys: Interacting with car computers |

Tech Tip Guys: Interacting with car computers

Recently my check engine light came on, and I have no idea why. Is there some way to interface my smart phone or tablet with the car so I can determine what’s wrong and take the appropriate course of action?

Starting in the ‘70s and ‘80s, the EPA required all new cars to include OnBoard Diagnostics (or OBD). This software monitors the status of the engine and the car, and has obviously grown more comprehensive and functional, and the standard was upgraded to OBA II in 1996. (For more information on OBD and the EPA, check out these sites: and If you search the web for “OBD II,” you’ll find a large number of small handheld devices that you can plug into the port that every modern car includes for just this purpose, but unless you’re in the business of working on cars, it’s hardly worth the purchase.

Several companies provide hardware and software combinations that you can use to help diagnose your car. Again, these are totally overkill for the “casual” user, but you can find one such product here: This product includes a hardware piece you hook up to the car, and a software piece you run on a Windows PC that interprets information from the hardware. You can find a product that runs on iPhones and Android devices here: This software again requires a hardware device to connect your handheld device to the car. It’s not expensive, but may be too technical for the casual user.

Ken recently ran across a consumer-oriented device and software combination, available for pre-order at This simple-to-use device plugs directly into the hardware port on your OBD II-supported car, and transmits information wirelessly to your phone. It’s geared for end-users, not car mechanics, and it’s relatively inexpensive. Being a gadget-focused fellow, he ordered one immediately, although it still hasn’t shipped so we’ll have to reserve comment until he gets a chance to try it out.

Finally, there is another option—many auto parts stores have the OBD readers available, and can at least tell you why your Check Engine light came on, and many will read the car’s settings for free (assuming that you’ll spend money on parts and services to fix whatever the problem is.) AutoZone, for example, provides this service, we hear.

Loan your Mac to a friend

I need to loan my Mac to a friend, but don’t want him to be able to access my personal files. How can I let him use the machine, but not my content?

It’s probably best to keep friends from examining your personal files too closely, and the Mac operating system, OS X, makes this simple. All you need to do is create a new user account on the Mac and tell your friend the credentials to log into that account.

To create a new user account, start System Preferences, and then select to the Users and Groups option. You will need to unlock the settings so that you can make changes and then add a new user. Supply a password for the new user, and then you’re all ready to loan them your Mac.

Your friend will be able to log into the new account you created, but won’t be able to access your personal files. When the new user attempts to do so, the computer will display a get a warning indicating that the files aren’t available for this user. There’s really nothing your friend can do without knowing your password and logging into your account to get into your content.

It’s very safe, and this mechanism provides a great way to share the computer with other users. (If you’re really paranoid, you might want to consider also encrypting your data, but that’s a topic for a separate tip.)

Doug Behl and Ken Getzspent years answering technical questions in private, and are minimizing the questions by pre-emptively publishing the answers. Hear Doug and Ken’s tech tips on KNCO radio weekdays at around 8:21a.m. and 5:38 p.m.; find full write-ups including links to the products they mention at http://blog.techtipguys. com. Submit your own technical questions to

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