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MULTI-MODEL - MIL ILLUMINATION WITH DTC P0128
Some vehicles may experience the MIL illumination with DTC P0128 (Coolant Thermostat Stuck Open) stored in memory without any problem on the ECT sensor and the IAT sensor. For example, this symptom may happen when driving after 1 to 1-1/2 minutes of idling with the heater and defroster ON after a cold start in cold conditions about 1°C (33-35°F). This condition may be caused by improper PCM calibration.
Customers having this concern should have their vehicle repaired using the following repair procedure.