The engine coolant is not reaching the expected temperature within a specified time.
Informational only. Consult a qualified mechanic.
Replace the thermostat. This is a common and inexpensive repair.
The P0128 OBD-II diagnostic trouble code (DTC) indicates: coolant thermostat below temperature. This is a low-severity powertrain code that your vehicle's onboard diagnostics system triggers when the engine coolant is not reaching the expected temperature within a specified time. If your check engine light is on with this code, the vehicle is generally safe to drive, but you should have it inspected soon.
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