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Home >> Infiniti >> 2002 >> I35 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0128: Thermostat Function >> DTC Confirmation Test
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DTC Confirmation Test

  1. Replace thermostat with an OEM replacement. Turn ignition on. Select COOLAN TEMP/S in DATA MONITOR mode with scan tool. If COOLAN TEMP/S is less than 140°F (60°C), go to next step. If COOLAN TEMP/S is not less than 140°F (60°C), allow engine to cool.
  2. Drive vehicle at a speed of 50-75 MPH for 10 consecutive minutes. 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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