In order to help the driver maintain their vehicle, manufacturers have been using computers and sensors to monitor just about everything in a car. Modern cars are sophisticated enough now to detect when any exterior lights have stopped working. When a bulb goes out, the overall resistance in the circuit changes, which then affects the voltage for that circuit. The computer monitors the circuits for all of the exterior lights for any changes in voltage and then displays a warning light.
What the bulb failure light means
The computer will switch on the bulb failure warning light when it detects any non-normal voltage in any of the bulb circuits. If you see the light come on, check all of the bulbs to find the one that is not working. Be thorough when checking the lights as modern cars have quite a few that can turn on the warning light. Some harder bulbs to find include license plate bulbs, turn signals on the side mirrors, the yellow parking lights at the front of the vehicle, and the tail lights at the back that come on with the headlights.
When you find the bad bulb, replace it and the warning light should turn off. It is possible for false positives to occur in which case the entire circuit would need to be inspected for any damage.
Is it safe to drive with the bulb failure light on?
In most cases, the car is still driveable. Now this doesn’t mean you should ignore the light. The exterior lights are very important for warning surrounding drivers of your car’s position and actions. Having non-functional lights can also make you responsible for damages in the event of a collision.
If you need any help replacing bulbs or if the light won’t turn off, our certified technicians are always available to assist you.
This article originally appeared on YourMechanic.com as What Does the Bulb Failure (Exterior Light Fault, License Plate Bulb, Brake Light Bulb) Warning Light Mean? and was authored by Spencer Cates.