Repair EDC15C6 MB sprinter 2.2 with P1661

[SR71]

Hello Guys,

I'm looking for a method to repair an ECU EDC15C6 with P1661 Fault code.
Wich components should i replace.
The car starts with another ECU.

Thanks in advance

P1661 : Injector voltage (too low) or Capacitor voltage 1 (Low voltage)