I know nothing about the code - only what I see from your example, so this reply might be totally bogus.

In the example, the lowest nibble is always F and the third nibble is always 0. If this is always true, you can simply use shift to strip them off and put them back. In the first case (OBC1), shift 7F >> 4, to get 7. Then add it to 80, and store 87. To recover, use logical AND to recover the low nibble. Subtract that from the stored value to get the high byte, then shift it << 4 and add F to get the low byte back.