The factory DEF heater on certain vehicles often fails from fluid intrusion. This Dorman OE FIX solution modifies the OEM design to address this failure point and increase reliability. This part is compatible with the following vehicles. Before purchasing, enter your vehicle trim in the garage tool to confirm fitment. [Mercedes-Benz GL320: 2007, 2008, 2009] - [Mercedes-Benz GL350: 2010, 2011, 2012]