Here are the steps to fix the parity when solving a 4×4 rubik’s cube:
Edge Parity: RD1, T2, LD1, F2, LU1, F2, RD2, T2, RU1, T2, RD1, T2, F2, R2, F2
The abbreviations are as follows:
RD – Right Down
LD – Left Down
RU – Right Up
RD – Right Down
T – Top
F – Front