Why does my Coolant fan always stay on?

Your coolant fan may always stay on due to a malfunctioning thermostat, which can cause the engine to overheat and trigger the fan to run continuously. Another possibility is a faulty fan relay or switch that fails to turn off the fan when the engine reaches the appropriate temperature. Additionally, issues with the engine's temperature sensors can also lead to incorrect readings, keeping the fan running. It's advisable to have a mechanic diagnose the problem to prevent potential damage to your engine.