9012/9006/9005 LED decoders are used for fixing the malfunction of not light up for flickering on and off after installing the led bulbs for American and European vehicles due to the led bulbs draw much less current than stock lamps.
This kits usually are not compatible with Japanese vehicles with LED DRL flickering. For fixing LED DRL flickering, it is recommended to choose the 9005 LED DRL anti-flickering harness kits.
For most vehicles, LED bulbs just plug and play, easy installation. For some European vehicles, extra LED resistors or decoders or DRL anti-flickering harness maybe required to avoid the flickering or error code.