What typically indicates a cooling system leak?

A cooling system leak is commonly indicated by the presence of coolant puddles under the vehicle. When there is a leak in the cooling system, coolant can escape from the radiator, hoses, or engine components and pool on the ground. This visible sign makes it easier to identify the problem and take necessary steps for repair.

The other options do not serve as direct indicators of a cooling system leak. Black smoke from the exhaust usually points to a fuel mixture issue or engine combustion problem, while low fuel efficiency might highlight a variety of mechanical or tuning problems unrelated to the cooling system. Frequent brake failure suggests issues with the braking system itself, which is entirely separate from cooling system functionality. Thus, the presence of coolant puddles is the most immediate and reliable indication of a cooling system leak.