What it means
This warning usually shows a thermometer in liquid or a red temperature symbol. It means the engine coolant temperature is higher than normal, which can lead to serious engine damage if ignored.
What to do first
- Pull over safely and turn off the engine.
- Wait at least 15–30 minutes before opening the coolant cap — hot coolant can spray and burn.
- Check for steam, sweet smell, or visible leaks under the car.
- Check coolant level only when the system is cool, if you know how to do so safely.
Common causes
- Low coolant level or leak
- Faulty thermostat
- Cooling fan not running
- Blocked radiator or airflow issue
- Water pump failure
When it is most serious
Stop immediately if you see steam from under the hood/bonnet, smell coolant, hear boiling, or lose power. Driving an overheating engine can warp the cylinder head or cause costly damage.
Coolant Temperature Warning FAQ
Can I add water if coolant is low?
Only when the engine is cool and you use the correct coolant mix recommended in your manual. Plain water is a temporary emergency measure on some vehicles, not a long-term fix.
Why did the light come on in traffic?
Low airflow at idle, a weak fan, low coolant, or a stuck thermostat can trigger overheating in stop-and-go driving.
Related symbols
Dashboard symbols vary by make and model. Always confirm the exact meaning in your owner's manual.