there are such devices that "talk" to the computer in your car and tells you what is wrong with the car by codes which you can either look up in a book or use with computer software through a USB connection. The only problem is that they're expensive and relatively hard to find if you dont know where to look. There are however several places that you can rent these devices relatively cheaply.

Yep, can be done. I do electronic diagnostics work for a large car manufacturer in the UK, and the dealership's diagnostic machines are available to us on the company network. I haven't looked in to the nature of the network, but I think they're essentially VPN'd into our intranet. The machines keep records of the historic diagnostic sessions, and we can control them remotely. However, because of the business relationship between the dealerships and the manufacturer, the information on the diagnostic machines is confidential and we need to jump through hoops to get at it.

Technically, we could roll out exactly what you've described tomorrow. There are a couple of other issues, though: the diagnostic connectors aren't cheap enough for the end-consumer market, and some of the details of the diagnostic protocols are considered to be confidential (makes no sense to me, but there you go). The latter could potentially mean that, for example, the airbag system on your Corsa performs a destructive self-test in response to a command that would turn the radio volume up in my A-class. I've never heard of that sort of problem actually happening, by the way, but it's certainly conceptually possible, and as far as I'm aware there is no accepted standard for the car to actually report what it is, so the diagnostic system would have to essentially make a guess that it was plugged into the correct type of vehicle. That creates a legal quagmire, unfortunately.

the only problem would be the interface between the car and the computer, plug ins vary between manufactures if they all decided to use usb or parrallel port connections that would be great but as long as an atypical plug can garantee that only licensed personel with access to that interface plug can do the work that simply isnt going to happan. however with new cars equiped with onstar a diagnostic can be run remotely as long as your carphone has cell service.

I really like this idea, would stop unscrupulous mechanics from ripping you off for work that did'nt need doing. You would have to be careful that someone did'nt try to 'write' or download some virus type software into your engine management computer while you had the car hooked up to the internet though, firewall software might help.

Hey, just reading around on some forums, and I'm huge on new innovation that is found on the web. I have a 1996 BMW and usually I pay at least $200 to get my car diagnosed. Luckily I found this site and I was able to diagnose my car for free and found a cheap mechanic through that site to work on it for a cheap price. So you may want to check out www.automd.com to get everything for free. It even alerts you via email to let you know when your car needs a tune up, oil change, and wheel rotation. And if worst comes to worst and I need to go to the BMW mechanic I don't get ripped off anymore because I come in prepared on what is going on with my car and I come in educated and they don't and can't rip me off!!! So everyone who's sick of getting ripped off check out this site.. www.automd.com

Can be done, but you still need someone knowledgeable at the car. The cars computer only sees faults in a particular circuit, so if you hook it up, and it points to a "throttle position sensor", means it could be a faulty sensor, faulty wiring, or even a fauly computer. Point is, you still need knowledge on how and what to diagnose that the average consumer does not have. There are rip-off shops just like any business, take your car to someone you can trust, and then stick with that place. Vehicle diagnostics can be very tough, and the "rip-off" part comes in when inexperienced techs guess at parts...they have to charge someone for parts. A bigger gripe too me is medical doctors....talk about "guess work" Good Lord!!! And you get charged whether they fix you or not, what's up with that!!!!

i believe its GM but i know at least one car company in the US does do this... they can send you and e-mail when your oil needs to be changed, and if theres any other problems your not aware of...