framework, and lasts only a few seconds. The light check consists in sending weak electrical impulses on the headlights to "probe" if there are bulbs installed. Original halogen incandescent bulbs, or xenon kits, absorb these faint pulses without lighting up. Different speech for LED lamps, which are super sensitive even to weak electrical impulses, sufficient to make them partially illuminate. Hence the "safety car" effect which lasts only a few seconds during the check. It does not depend on the LED lamp and only some cars do it including some Minis and some BMWs. The canbus filters, by their very nature, only solve canbus compatibility problems (constant flicker with the engine running, warning lights on the dashboard, radio interference), but they do not have a decisive effect on the check-lights of a few seconds with the engine off.