My Service Engine light has been on since the exhaust was dropped to install a new transfer case last winter. I assume the O2 sensor(s) was disturbed . The rover runs fine. So last night after the oil change I dumped into the gas tank a bottle of Prestone Fuel injector cleaner. Now the Check Engine light is also on. The owners manuel says that the CE light is a fuel injector problem or an emmision problem. Did the injector cleaner cause the problem? Coincidence? Will the CE light go out if the problem cleans it self?(yea right)Any insights would be appreciated. Thanks.