* Overheating: This is the most common reason. The engine is getting too hot, triggering the cooling fan to run constantly to try and cool it down. The check engine light illuminates because the onboard diagnostics (OBD) system detects a high coolant temperature or other related issue.
* Low Coolant Level: Insufficient coolant means the engine isn't being cooled effectively, leading to overheating. Check your coolant reservoir to see if the level is low.
* Faulty Thermostat: A stuck closed thermostat prevents coolant from circulating properly, causing the engine to overheat.
* Faulty Water Pump: A malfunctioning water pump won't circulate coolant efficiently, resulting in overheating.
* Radiator Problems: A clogged radiator, damaged radiator fins, or a leak in the radiator can hinder the cooling system's ability to dissipate heat.
* Faulty Cooling Fan: While the fan is running, it might not be working efficiently. It could be running too slowly or intermittently.
* Sensor Issues: A faulty coolant temperature sensor can give inaccurate readings to the engine control unit (ECU), leading to the check engine light and fan activation.
* Head Gasket Failure: In severe cases, a blown head gasket can allow coolant to leak into the cylinders or oil, leading to overheating and potentially significant engine damage. This is less likely if the overheating is relatively recent, but it's still a possibility.
What to do:
1. Do NOT open the hood immediately if you suspect overheating. The coolant is extremely hot and can cause serious burns. Allow the engine to cool down completely before attempting any inspection.
2. Check the coolant level. If it's low, add coolant (after the engine has cooled) *only if it is safe to do so*. Do not remove the radiator cap when the engine is hot.
3. Have the vehicle diagnosed by a mechanic. The check engine light will have stored a diagnostic trouble code (DTC) that a mechanic can read using an OBD-II scanner to pinpoint the exact problem. Ignoring the issue can lead to severe and costly engine damage.
Don't drive the vehicle until the problem is diagnosed and fixed, especially if the engine is overheating. Continuing to drive could cause significant engine damage.
