Bulb failure light is a warning light that comes on in the instrument panel of some cars. It is usually triggered when a bulb in the car's lighting system has burned out. Depending on the car, the bulb failure light may be a separate warning light, or it may be incorporated into another warning light, such as the check engine or brake system warning light. When the bulb failure light comes on, it is important to have the burned-out bulb replaced as soon as possible. Depending on the car, the bulb failure light may only indicate that a bulb has burned out, or it may also indicate that a bulb is about to burn out. In some cases, the bulb failure light may also indicate other problems with the car's lighting system, such as a faulty headlight aim.