Reductant Injector
WARNING: This page is about a different car, the 2021 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.
The reductant injector is a PWM solenoid controlled directly by the PCM. The injector receives DEF (diesel exhaust fluid) from the reductant pressure line and sprays it into the exhaust stream, where it is mixed into the exhaust gases before entering the SCR.