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Home >> Toyota >> 2004 >> Highlander Limited, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 891 (Engine Control System (Diagnostic Codes & Symptom Tests)) >> DTC/Circuit Diagnosis >> DTC P0128: Thermostat Function >> On Board Diagnosis Logic

On Board Diagnosis Logic

WARNING: This page is about a different car, the 2013 Nissan Armada. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: If DTC P0128 is displayed with DTC P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307 or P0308, first perform the trouble diagnosis for DTC P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308. Refer to "DTC CONFIRMATION PROCEDURE ".

Engine coolant temperature has not risen enough to open the thermostat even though the engine has run long enough.

This is due to a leak in the seal or the thermostat stuck open.

DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0128
0128
Thermostat function The engine coolant temperature does not reach to specified temperature even though the engine has run long enough.
  • Thermostat
  • Leakage from sealing portion of thermostat
  • Engine coolant temperature sensor