If your vehicle is showing engine temperature gauge reads hot or pegs to the red, here are the most likely causes and the parts you'll need to fix each one.
The most common reason for overheating is simply a lack of coolant due to a leak in a hose, the radiator, or the water pump.
The thermostat regulates coolant flow to the radiator. If it fails in the closed position, hot coolant is trapped in the engine block.
If the cooling system wasn't properly bled after recent maintenance, trapped air bubbles will block coolant flow and cause rapid overheating.
If the electric cooling fan, its relay, or a mechanical fan clutch fails, no air is pulled through the radiator, causing the engine to overheat at idle or low speeds.
Sometimes the engine isn't actually overheating, but a failing sensor or wiring short sends a false maximum reading to the dashboard gauge.
The water pump circulates the coolant. If its internal impeller degrades or the drive belt breaks, coolant stops moving entirely.
A severe internal engine failure that allows superheated combustion gases to enter the cooling system, rapidly over-pressurizing and overheating it.