Engine Coolant Temperature Warning
Critical — Stop driving
What It Means
Engine coolant temperature has exceeded safe operating range. Overheating can warp cylinder heads, blow head gaskets, and cause permanent engine damage. This light may be red (overheating) or blue (engine cold — normal on startup).
Common Causes
- Low coolant level (check reservoir when engine is COLD)
- Coolant leak (radiator, hoses, water pump, head gasket)
- Failed thermostat (stuck closed)
- Failed water pump
- Clogged radiator (internal or external)
- Cooling fan not operating
- Blown head gasket (combustion gases entering coolant)
Can I Still Drive?
Red light: pull over and shut off the engine immediately. Wait at least 30 minutes before checking coolant — opening a hot radiator cap will cause severe burns. If coolant is full and engine was not severely overheated, drive short distances to a shop. If steam or coolant is visible, tow.
Estimated Repair Cost
$50 – $3,500
This is an estimate only. Actual costs vary by vehicle make, model, year, location, and shop labor rates. Always get multiple quotes for major repairs.
Related OBD-II Trouble Codes
These OBD codes are commonly associated with this warning light. Scan your vehicle with an OBD-II scanner to get the exact code before diagnosing.