What is a common sign of low coolant in an engine?

Overheating is a common sign of low coolant in an engine because coolant is essential for regulating the engine's temperature. It absorbs heat generated during combustion and helps maintain optimal operating conditions. When the coolant level is low, the engine loses its cooling capacity, leading to elevated temperatures. This can cause various issues such as engine damage, overheating components, and potentially severe mechanical failure if not addressed promptly.

While increased horsepower, reduced acceleration, and higher fuel consumption can be related to various engine performance issues, they are not direct indicators of low coolant levels. Instead, they reflect different mechanical or operational problems that would require separate diagnostics unrelated specifically to a coolant deficiency.