Look at 4 on the bottom picture. Then relate that to the second and then to the 3rd pic. Figured I would be the first to figure it out. And the sensors are around $30-40 at advanced Auto, AutoZone, O'Reilly etc....
That looks like the DEF Injector. I have had to replace the #2 sensor which is described as the Carbon Level Sensor, still an O2 sensor, in my wife's Jeep GC eco. It had set a code, cleared, set again, replaced with OEM as the aftermarket did not cover, that was two years back. $185.00.
