When should hazard lights be on?

Hazard lights should be activated when there is a mechanical problem either while driving or when stopped. This use signals to other drivers that your vehicle is experiencing an issue and that they should exercise caution. It serves as a warning that the vehicle may not be in normal operating condition, decreasing the risk of collisions by making your car more visible and alerting others to slow down or navigate around you safely.

In the context of the other options, hazard lights are not typically used during routine situations like heavy traffic, making a U-turn, or solely in bad weather conditions. Instead, they are specifically reserved for emergencies or situations where your vehicle is not able to proceed safely, thereby ensuring clearer communication with other road users about your circumstances.