What's the clicking sound in front of the car after the flameout?

This is due to the sound made by the engine when it expands with heat and contracts with cold. It's normal. Don't worry.

When the engine is working, the temperature of each part is different. Generally, the cylinder block temperature will not exceed100 C, while the exhaust pipe temperature will reach 400 ~ 500°C, and the three-way catalyst temperature will reach 600 C. Therefore, the expansion of these parts is also different.

When the engine stops working, it will gradually cool down under the influence of ambient temperature. At this time, the temperature of the exhaust pipe and three-way catalyst with high temperature will drop faster and the deformation will be greater, while the temperature of the engine block will drop slightly slower. Because of the inconsistent deformation, the two will rub at the joint, and we will hear the sound of "da da da".