Dear Tom and Ray:

My local automotive-repair shop offers a service in which they will "re-flash" your car's computer. Is that helpful, or just an unnecessary service to generate profits for the shop? Is it something I could do myself with one of those $150 scan tools from the auto-parts store? The shop claims the "flashing" will remove false engine codes, increase engine performance, improve gas mileage, etc. So what do you think?

-- Dan

TOM: Gee, I thought that was illegal. Last time my brother flashed someone at the garage, he spent 30 days in jail.

RAY: This is not something you can do yourself with an inexpensive scan tool, Dan. The equipment required to re-flash the car's computer costs several thousand dollars. And there are different machines for different manufacturers.

TOM: The good news is, there's no reason to "re-flash" your computer's memory as a maintenance service.

RAY: The primary reason to re-flash a computer (which basically means updating or reinstalling its software) is that an update has been issued by the manufacturer.

TOM: If the update is to address a serious drivability or safety issue, you or your dealer will be notified by the manufacturer that there's a software update, and that it's recommended for all vehicles. Dealers often will do that for free, especially if you're in for something else.

RAY: The other reason we'll re-flash a computer is if we already have our machine hooked up to the car for some other reason. It's a very simple procedure, and there may be minor updates that the car hasn't had. The manufacturer may have tweaked the transmission-shifting algorithm or some other parameters that are not crucial but may bring slight improvements to drivability, mileage or emissions.

TOM: So if your shop has the capacity to re-flash your computer, and they're not going to charge you too much for it, it can't hurt anything, and it might be useful.

RAY: But as long as you haven't received a notification from your manufacturer, there's no need to re-flash anything on a regular basis except your chimney.