P0128 Kia Telluride
Coolant Thermostat Below Regulating Temperature · Powertrain Code · Medium · Repair: Easy
What is P0128?
The engine coolant is not reaching the expected temperature. Most commonly caused by a stuck-open thermostat, low coolant level, or a faulty coolant temperature sensor.
When the Kia Telluride triggers code P0128 (coolant thermostat below regulating temperature), it typically points to an issue in the powertrain system. Below you'll find the most common causes, symptoms, and repair options specific to the Kia Telluride.
This repair is rated easy, meaning basic tools, no lift needed.
Diagnostic data on this page is compiled from publicly available repair resources and technical service bulletins. Always have a qualified mechanic confirm the diagnosis before authorizing repairs on your Kia Telluride.
Common Causes on Kia Telluride
- Thermostat stuck open on 3.8L Lambda V6 engine
- Coolant temperature sensor drift from age or connector corrosion
- Thermostat housing gasket deterioration from extended service interval
- Low coolant from water pump gasket seepage
Symptoms
- Engine takes abnormally long to reach operating temperature
- Heater blows lukewarm or cold air
- Temperature gauge stays below normal or never reaches middle
- Slightly reduced fuel economy from extended open-loop operation
- Check engine light illuminated
Notes for Kia Telluride
Palisade and Telluride 3.8L V6 thermostat is accessible from the top of the engine.