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Home >> Mitsubishi >> 1998 >> Eclipse GSX, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - 2.0L Non-Turbo >> Diagnostic Tests >> DTC 128: Closed Loop Temperature Not Reached

DTC 128: Closed Loop Temperature Not Reached

NOTE: For terminal identification, see TERMINAL IDENTIFICATION  . For circuit and wire color identification, see WIRING DIAGRAMS article.
  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 operates as specified, go to next step. If thermostat does not operates as specified, replace thermostat.
  2. Disconnect Engine Coolant Temperature (ECT) sensor connector. Check resistance between ECT sensor terminals. Resistance range is 9000-11,000 ohms at 77°F (25°C) to 600-800 ohms at 212°F (100°C). If resistance is as specified, go to next step. If resistance is not as specified, replace ECT sensor.
  3. Check PCM connectors, ECT sensor connector, junction connector and wiring harness between PCM and ECT sensor. If wiring and connectors are okay, replace PCM.
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