When the "check engine" light onyour dashboard goes on, it usually meansa trip to a mechanic to find out what'sgoing on. Now, car dealers can plug anelectronic gizmo called Networkcar (858-450-3245; www.networkcar.com) intoyour car that will diagnose the problemand send a wireless signal to the dealer'sservice area. The service manager thensends you an e-mail suggesting that youcome in for servicing. Plagued by shrinkingprofit margins on new- and used-carsales, dealers are looking to their serviceshops to beef up the bottom line, anditems such as Networkcar may pick upsome of the slack. Dealers charge $500and up to install the device and you'llpay about $9 a month for the serviceafter the first year. Networkcaralso has a built-in global positioning systemthat can help foil car thieves.