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Home >> Infiniti >> 2003 >> FX35 AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0128: Thermostat Function >> DTC Confirmation Procedure
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DTC Confirmation Procedure

NOTE: If DTC confirmation procedure has been previously conducted, always turn ignition switch to OFF position and wait at least 10 seconds before conducting the next test. For best results, perform at ambient temperature and engine coolant temperature of 14°F (-10°C) or more.
  1. Replace thermostat using only a Nissan thermostat a replacement. If an incorrect thermostat is used, the MIL may illuminate.
  2. Turn ignition switch to ON position.
  3. Select COOLAN TEM/S under DATA MONITOR mode using either CONSULT-II or GST.
  4. Ensure COOLAN TEM/S is more than 140°F (60°C). If less than 140°F (60°C), go to next step. If more than 140°F (60°C), stop engine and let engine cool to less than 140°F (60°C), then begin again at step  1.
  5. Drive vehicle for 10 consecutive minutes at 50-75 MPH.
  6. 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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