P0128: Coolant Thermostat (Coolant Temp Below Thermostat Regulating Temperature)
MediumPowertrainCooling System
What does P0128 mean?
P0128 is a diagnostic trouble code indicating "Coolant Thermostat (Coolant Temp Below Thermostat Regulating Temperature)". This code relates to your vehicle's cooling system and should be diagnosed to determine the root cause. The severity level helps indicate how urgently this should be addressed.
Common causes
- Stuck thermostat (open or closed)
- Low coolant level or coolant leak
- Failed coolant temperature sensor
- Faulty water pump
- Blocked radiator
What should you do?
Schedule a diagnostic appointment at your earliest convenience. The vehicle is generally safe to drive short distances, but the underlying issue should be addressed to prevent it from worsening.
Get a diagnosis for YOUR car
Code P0128 can mean different things depending on your vehicle. TorqueBot gives you a diagnosis specific to your make, model, and year.