14MM. Your best bet is to buy the special MB plug wrench. There is not enough room between the transmission tunnel and plug to use much of anything else.<br> <br> Good luck,<br> Larry
BenzWorld.org forum is one of the largest Mercedes-Benz owner websites offering the most comprehensive collection of Mercedes-Benz information anywhere in the world. The site includes MB Forums, News, Galleries, Publications, Classifieds, Events and much more!