Inspection Check
Headlamp aim
The vertical and horizontal alignment of the dipped beam. Measured at MOT against tolerances in the inspection manual.
An out-of-spec headlamp aim is a Major defect — too high dazzles oncoming drivers, too low cuts useful range. Aim can drift after heavy loading, suspension work or a replacement headlamp unit.
Many self-levelling LED and Xenon systems perform a brief beam dance on startup to recalibrate; if the warning light stays on, the system has faulted and the lamp will not adjust correctly.