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Home › Mitsubishi › 1995 › Eclipse GS, Automatic › Repair and Diagnosis › Engine Performance › System › Engine Controls - Tests W/Codes - 2.0L Non-Turbo › Diagnostic Tests › Code 128 - Closed Loop Temperature Not Reached

Code 128 - Closed Loop Temperature Not Reached

NOTE: For component terminal identification, see TERMINAL IDENTIFICATION  in this article. For appropriate WIRING DIAGRAMS, see WIRING DIAGRAMS  section.
  1. Remove thermostat. Check that valve closes fully at room temperature. Place thermostat in container of hot water. Raise water temperature, check that thermostat begins to open at 195°F (90.5°C) and is fully open at 216°F (102°C). Valve lift is .31" (8 mm) from full closed to full open. If thermostat is within specification, go to next step. Replace thermostat if not within specification.
  2. Disconnect coolant temperature sensor connector. Measure resistance between sensor terminals. Resistance range is 9000-11,000 ohms at 77°F (25°C) to 600-800 ohms at 212°F (100°C). If sensor resistance is within specification, go to next step. If sensor resistance is not within specification, replace temperature sensor.
  3. Check PCM connector, temperature sensor connector, junction connector and wiring harness between PCM and coolant temperature sensor. If wiring and connectors are okay, replace PCM.
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