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DTC P0128 Thermostat Malfunction: Description

This DTC is output when the Engine Coolant Temperature (ECT) does not reach 75°C (167°F) despite sufficient engine warm-up time.

DTC DETECTION CONDITION CHART

DTC No. DTC Detection Condition Trouble Area
P0128 Conditions (a), (b) and (c) are met:
  1. Cold start
  2. Sufficient warm-up time has elapsed
  3. ECT is less than 75°C (167°F)
  • Thermostat
  • Cooling system
  • ECT sensor
  • ECM
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