I've got a 2004 E320 cdi with the brabus d6 tuning chip, is there a specific procedure to revert the car to stock after unplugging these boxes? every time I unplug the brabus tuning chip and start the car (as stock I'd think) it throws a check engine light on the dash and says fuel Rail pressure too high when using a diagnostic computer.. am I doing something wrong? is there something else I need to do other than just unplug the box?