Adblue(R) Control Unit, Component Description - GF49.20-P-0011A

Model 223 

with code U79 (BLUETEC (SCR) diesel exhaust treatment, generation 3) 

Courtesy of MERCEDES-BENZ USA

The numbers on the pins indicate the pin numbering of the slots.

Fig 1: Adblue(R) Control Unit Components Location - Model 223 With Code U79

Courtesy of MERCEDES-BENZ USA

Location