For the left headlight with HID (High Intensity Discharge), on certain vehicles, the sealing between the lens and the housing is not seated in a correct position due to the installation with wrong sized tool. Repeated turning on and off the headlight can cause such sealing to partially come off, which could allow water to enter the inside of the headlight when driving in rain. If that water falls into the control unit located below the inside of the headlight, it may cause a short circuit in the voltage control circuit, in which case the headlight will fail.