A thermometer-in-liquid dashboard icon, red for overheating and (on some vehicles) blue for an engine that is still too cold.
Also known as: Engine temperature light, Overheating light
Warns that engine coolant temperature is outside its safe operating range; per ISO 2575's own stated colour rule, red denotes 'too hot' and blue denotes 'too cold' when the same base symbol is reused for both states.
Red illumination warns the engine is overheating and is generally treated as a 'stop the vehicle' warning; the same pictogram shown in blue instead indicates the engine is still below normal operating temperature, per ISO 2575's own stated colour convention for heating/cooling symbols.
Contexts: Vehicle dashboard
Related forms that are not treated as separate canonical symbols — see our variant rules.
Cold-engine (blue) variant
The same thermometer-in-liquid pictogram shown in blue indicates the engine has not yet reached normal operating temperature — informational, not a fault.
A thermometer shape partly submerged in a wavy line representing liquid.