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Home › Infiniti › 2003 › FX45 › Repair and Diagnosis › Engine Performance › System › Engine Controls - Self-Diagnostics › Diagnostic Tests › DTC P0128: Thermostat Function › DTC Confirmation Test

DTC Confirmation Test

NOTE: For best results, perform at ambient temperature of 14°F (-10°C) or higher. Also, perform at engine coolant temperature of 14°F (-10°C) to 140°F (60°C).
  1. Replace thermostat with new one. Use only a genuine NISSAN thermostat as a replacement. If an incorrect thermostat is used, the MIL may come on.
  2. Turn ignition switch on. Select COOLAN TEMP/S in DATA MONITOR.
  3. Check if COOLAN TEMP/S is above 140°F (60°C). If it is below 140°F (60°C), go to next step. If it is above 140°F (60°C), stop engine and let cool down to less than 140°F (60°C), then retest from step  1 .
  4. Drive vehicle for 10 consecutive minutes at 50-75 MPH.
  5. If 1st trip DTC is detected, go to DIAGNOSTIC PROCEDURE  . If 1st trip DTC is not detected, system is okay at this time.
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