The indicator relay for a left-hand drive Peugeot Boxer is located behind the instrument panel, on the left-hand side, above the steering column. It is a small black or grey box with a ribbed surface, roughly 2 inches long and 1 inch wide. It is typically attached to the back of the instrument panel with a single screw or push-on clip.
If you don’t see it you may need to remove one or more trim pieces to reveal the turn signal flasher. They usually pull straight off by hand, or may be secured by a single screw or plastic push pin or clip.