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P0128 on the 2017 Hyundai Ioniq

The bulletins listed name this code in NHTSA's summary, or are about the same components. A bulletin or a recall listed here may apply to the model year. None of it is a diagnosis.

Nobody has written a description of this code yet.

Bulletins for this model year that name P0128
20-FL-012H2021-01-09. Service bulletin. This bulletin provides information related to the Engine Control Module (ECM) software logic update for DTC P0128 “Coolant thermostat - Coolant temp Below thermostat regulating Temperature”. There is no drivability issue with this DTC.

1 on file from NHTSA, as of 2026-10-19. See them in the bulletin list. A bulletin lists model years: read the document for which vehicles it concerns.