A convertible top, having a linkage for displacing the top, a roof tip fixed to a front vehicle cowl in a closed position, a top lock which displacable between a locked and released position and secures the roof tip to the front cowl when the top is in the closed position and has a locking support having a pivotable locking hook and a locking counterpart which can be engaged with the locking hook, and a position detector which detects a relative position between the roof tip and the front cowl. The position detector has a sensor unit having at least two Hall-effect sensor elements, one of which switches at a first distance between the sensor unit and a magnetic element and the other one of which switches at a second distance between the sensor unit and the magnetic element, the second distance being different from the first distance.