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Home › Mitsubishi › 1997 › Eclipse Base, Standard › Repair and Diagnosis › Engine Performance › System › Engine Controls - Tests W/Codes - 2.0L - Non-Turbo › Circuit Tests › DTC 128 - Closed Loop Temperature Not Reached

DTC 128 - Closed Loop Temperature Not Reached

NOTE: For terminal identification, see TERMINAL IDENTIFICATION  in SELF-DIAGNOSTICS section. For circuit and wire color identification, see WIRING DIAGRAMS - 2.0L - NON-TURBO 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. Replace thermostat if it does not operate as specified.
  2. Disconnect Engine Coolant Temperature (ECT) sensor connector. Check resistance across 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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