P0128 on the 2004 Chrysler PT Cruiser
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.
| 18-016-13 | 2022-07-18. Service bulletin. This bulletin involves reprogramming the Powertrain Control Module with new software. The Technician may discover that P0128 - Thermostat Rationality DTC is present. This DTC is a two trip code and is matured if a significant difference exists between the PCM predicted and actual engine coolant temperature during engine warm-ups. The PCM calibration may improperly mature a P0128 DTC because the airflow across the coolant temperature sensor during colder ambient temperatures, 50° F (10° C) or below, causes the predicted coolant temperature to deviate from the actual coolant temperature. |
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| 18-016-13 | 2021-03-15. Service bulletin. This bulletin involves reprogramming the Powertrain Control Module with new software. The Technician may discover that P0128 - Thermostat Rationality DTC is present. This DTC is a two trip code and is matured if a significant difference exists between the PCM predicted and actual engine coolant temperature during engine warm-ups. The PCM calibration may improperly mature a P0128 DTC because the airflow across the coolant temperature sensor during colder ambient temperatures, 50° F (10° C) or below, causes the predicted coolant temperature to deviate from the actual coolant temperature. |
2 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.