I claim the ornamental design for a taillight lens cover for a vehicle, as shown and described.
FIG. 1 is a top plan view of taillight lens cover for a vehicle showing my new design;
FIG. 2. is a front elevational view thereof;
FIG. 3 is a left side elevational view thereof; and,
FIG. 4 is a left perspective view thereof.
The “taillight lens cover for a vehicle” is on the left side of the vehicle thereof; the right taillight design is a mirror image of the left side taillight design.