Coolant temperature warning light on? Understand overheating causes, what to do safely and why opening a hot cooling system can be dangerous.
Stop safely and let it cool
A red temperature warning usually means the engine is overheating or the cooling system has detected an unsafe temperature. Continuing to drive can turn a cooling-system fault into major engine damage.
Move to a safe place, switch the engine off and allow it to cool. Do not remove the expansion-tank or radiator cap while the system is hot or pressurised because hot coolant and steam can cause serious burns.
An engine can overheat even with coolant showing in the tank. A failed fan, thermostat, water pump, blocked radiator, trapped air or combustion-gas problem can all reduce cooling without an obvious low level.
Only follow the vehicle handbook when the engine has cooled sufficiently. A top-up may not fix the underlying fault, and repeated coolant loss needs investigation. If the temperature rises again, steam is present or coolant is pouring out, recovery is safer than continuing to drive.
Useful checks can include coolant level and concentration, visible leaks, cooling-fan operation, thermostat behaviour, pressure testing, water-pump circulation and evidence of combustion gases entering the cooling system.
Photograph the dashboard and AutoAid can help identify the symbol, ask follow-up questions and explain likely next steps.
Photograph the warning lightThe Highway Code advises drivers to understand dashboard warnings and not ignore signs that may indicate a serious developing fault. Your vehicle handbook remains the definitive source for the exact symbol and manufacturer-specific procedure.
AutoAid provides AI-assisted guidance only and never a guarantee. All faults, urgency ratings and prices are estimates — a physical inspection by a qualified mechanic may still be required.