Engine Coolant Temperature Light: what it means and what to do
Color: Red (blue on some cars = engine still cold)
Urgency: Red: urgent. Pull over and let the engine cool.
What it means
The engine is running too hot (or, if blue, has not warmed up yet).
Is it safe to drive?
No, if red. Overheating can warp the cylinder head or blow the head gasket. Never open a hot radiator cap.
Likely causes
- Low coolant from a leak
- Failed thermostat
- Bad water pump
- Radiator or cooling fan failure
- Head gasket failure
Typical cost ranges
Rough general estimates for US shops (parts and labor). Your price depends on vehicle, region, and shop.
| Repair | Rough range |
|---|---|
| Coolant flush/top-off | $100–$200 |
| Thermostat | $150–$400 |
| Water pump | $400–$1,000 |
| Radiator | $400–$1,200 |
| Head gasket | $1,200–$3,000+ |
What to tell the shop
Tell them how long you drove after the light came on, whether you saw steam or sweet-smelling fluid, and ask for a pressure test result.
Frequently asked questions
What does the Engine Coolant Temperature Light mean?
The engine is running too hot (or, if blue, has not warmed up yet).
Is it safe to drive with the Engine Coolant Temperature Light on?
No, if red. Overheating can warp the cylinder head or blow the head gasket. Never open a hot radiator cap.
What causes the Engine Coolant Temperature Light to come on?
Common causes include: Low coolant from a leak; Failed thermostat; Bad water pump; Radiator or cooling fan failure; Head gasket failure.
How much does it cost to fix the Engine Coolant Temperature Light problem?
Rough general estimates: Coolant flush/top-off: $100–$200; Thermostat: $150–$400; Water pump: $400–$1,000; Radiator: $400–$1,200; Head gasket: $1,200–$3,000+. Actual costs vary by vehicle, region, and shop.
What should I tell the mechanic?
Tell them how long you drove after the light came on, whether you saw steam or sweet-smelling fluid, and ask for a pressure test result.
General information only, not professional mechanical advice. Check your owner's manual, and if in doubt, stop safely and call for help.