The only reason I could think would be if somehow in the cleaning process, you'd accidentally wipe the programming. Only the dealer can reflash that, and I'm not sure if they'd do it to a damaged ECU. Lawyers and liabilities, y'know. Besides, I'm not sure what cleaning the PCB would do at this point. You'd probably just be better off removing the connectors and checking each for corrosion. If the board itself is damaged, unless you can replace the components (or even get the right ones in the first place) then you're just wasting your time and energy.
Has anyone checked the diagnostic codes lately? If water got into the sensors, that could be the reason for the errors and not the ECU.
Has anyone checked the diagnostic codes lately? If water got into the sensors, that could be the reason for the errors and not the ECU.