If the thermostat is stuck open, the engine will be slow to warm and may not reach normal operating temperature. As a result, performance of the heater will be poor. Fuel economy will probably deteriorate. And the vehicle may fail emissions testing (if this is required where you live). Furthermore, engine wear may be accelerated in the long term. For all of these reasons, if a thermostat is stuck open, it should be replaced as soon as possible.
It will run cooler, be inefficient and wear more quickly.
Overheating if stuck closed, no engine heat if stuck open.
Stuck open thermostat.
A thermostat can be stuck open or closed. If the engine runs to cool it is stuck open. If the engine is running hot it is stuck closed. If you don't have these problems you should'nt have to change it.
If the engine is overheating, the thermostat is stuck closed. If the heater is not putting out enough hot air the thermostat is stuck open. Change the thermostat as a normal part of maintenance when changing coolant.
The piston or spring on the thermostat could be stuck.
The thermostat is stuck open or missing.
A stuck closed thermostat can lead to severe overheating which can lead to severe engine damage which then leads to big money for repairs.
Thermostat is stuck open. Replace it.
Your KIA is either low on anti freeze or the thermostat is stuck and your engine is not operating at the correct temperature.
If the thermostat is stuck open, the engine will never warm up to proper temperature.
If it is stuck closed, the engine will overheat. If it is stuck open, the engine will take a long time to reach operating temp.