When you have to escape the sewer in the final part of the Der Flakturm mission there will be 6 Nazi Storm Elite super soldiers with MG42 heavy machine guns in your way and they are hard to kill. As it's nearly impossible to kill them all it's easier to try and run past them but to do this you will need at least 3 Health bars. When you get past them and then climb the lader the game is more or less over.

During gameplay press RB + LB and enter X, B, Y, A, A to access the 'Cheat' menu. Then enter the following codes to unlock the corresponding effect.

Unlock Full Ammo:
Hold LB + RB and enter B, B, Y, X, A, Y.

Unlock Full Health:
Enter Y, X, X, Y, A, B.