MERCEDES BENZ C300 DRIVETRAIN

I Am Changing My Rear Differential Fluid. I Believe The Correct Fluid Is 75w-90 For The Rear. My Question Is, Does The Front Differential...

Drives Well But I Have Codes U0001, U0002, And U0101. Read Somewhere That It Could Be Moisture In The Trunk On Right Side By Fuse Box. It...