The centres are solved, all edge groups are paired, and the first two layers of the reduced cube are solved.
Hold the cube with yellow up. Place an edge group with yellow facing sideways at top-front (UF).
1. Recognize OLL parity
Ignore the corners and count the edge groups with yellow facing up. Once the first two virtual layers are solved, a count of one or three indicates OLL parity. OLL refers to last-layer orientation.
Every edge group must already contain two matching wings. If a group has two unmatched wings, return to edge pairing. For OLL parity, look for a flipped edge group whose wings already match. If zero, two, or four edge groups have yellow facing up, use the ordinary 3×3 yellow-cross cases.
2. Place the target edge group at top-front
If three edge groups have yellow facing up, place the fourth group at UF. If only one group has yellow facing up, place any of the other three at UF. Flipping that group gives you an ordinary two-edge case.
Use a sideways whole-cube rotation or U before the sequence as needed. Keep yellow up at the start.
3. Follow the full repair sequence
Rw U2 x Rw U2 Rw U2 Rw' U2 Lw U2 Rw' U2 Rw U2 Rw' U2 Rw'
Work through the sequence in the groups shown below, keeping the letters in the same order.
Rw U2 xRw U2 Rw U2 Rw' U2Lw U2 Rw' U2Rw U2 Rw' U2 Rw'
Rw and Lw each turn two layers. For x, rotate the whole cube in the direction of R, then use the new face directions. Wait until the repair is complete before checking the centres.
4. Return to the solve
Once you’ve completed the full sequence, reorient the cube with yellow up. Check that the centres and edge pairs are restored. Count the edge groups with yellow facing up again. If the cross is still incomplete, return to the yellow-cross lesson.
This repair corrects the edge orientation. You may still need to solve other last-layer pieces to finish the cube, and PLL parity can still occur later in the solve.
Need a reminder of the move notation?
R right · L left · U top · D bottom · F front · B back. A plain letter means a 90° clockwise turn as you look directly at that face. An apostrophe (′) reverses the direction. A 2 means a 180° turn. Keep the same face toward you throughout the algorithm.
Rw turns the rightmost two layers together. 2R turns only the second layer from the right. 3Rw turns three layers. x rotates the whole cube like R, so the old front becomes the new top.
Watch, then try
Work through an example
Start by going through the example one move at a time. It shows a specific action from a prepared position. Use the lesson’s setup instructions to recognize when that action applies to your own scramble.
Watch one worked example
The prepared cube has its flipped pair at UF. Notice the whole-cube x rotation, two-layer wide turns, and the restored edge pair at the end.
Example grip: yellow up · blue front · red right at the start. Follow any written whole-cube rotations.
0 / 18
Loading 3D cube…
Prepared position · 0 / 18 moves
Use Next move to follow the sequence.
Drag to inspect other faces. Use the arrow keys to rotate the view when the cube has focus.
Copy this exact example on your own cube
Start with a solved 4×4, with yellow on top and blue at the front. Apply the setup below from left to right to create the example’s starting position. Keep this practice setup separate from the scramble you’re solving throughout the course.
Rw U2 Rw U2 Rw' U2 Rw U2 Lw' U2 Rw U2 Rw' U2 Rw' x' U2 Rw'Then follow the lesson sequence. If your cube’s colour scheme differs, match the piece relationships using your own colours.
Compare the starting position and the result
Drag each cube to inspect its other faces.
Explain it to yourself
Check your understanding
Now use your own cube
Your turn
If you encounter this case during a solve, pause at the yellow-cross step. Put the target at UF, complete every move in the sequence, then return the cube to yellow up and identify the new yellow-cross case.
Open a 4×4 Digital Cube for practiceOpens in a new tab so you can keep this lesson open while you practise. Check for yourself whether you’ve met the lesson goal. The Digital Cube doesn’t grade your work.
If you get stuck
The front face in the animation changed during the sequence.
For x, rotate the whole cube and use the new face directions for the remaining moves.
My cube is still unsolved after the parity repair.
Recheck the yellow cross and continue with the usual last-layer steps. This repair corrects only the flipped edge group.
Before moving on
Check your result
Your cube at this stage
Flipped edge group corrected
The edges are paired and yellow-edge orientation is back to normal. This example has a yellow cross, and the corners still need solving.
Confirm these on your cube. Watching the animation alone does not complete the lesson.
Check off each item once you can do it yourself.