Is my scab infected if it is turning yellow? what color usually means that it is infected?

Red with pus: Swelling, heat, pain, pus, and redness are all signs of infection. Sometimes, within a scab, we can develop a yellow film on the healing tissue which is not pus, but rather, fibrin. This is actually a sign of good healing.

Not necessarily: But if you have ^'ed swelling, redness, tenderness, red streaking , increased pain or fever those could be related to infection.