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Home >> Infiniti >> 2015 >> QX60 Base, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 40 (Engine Control System (DTC/Circuit Diagnosis) (VQ35DE) (Except Hybrid) (1 Of 3)) >> DTC/Circuit Diagnosis >> DTC P0128: Thermostat Function >> DTC Logic >> DTC Detection Logic

DTC Detection Logic

WARNING: This page is about a different car, the 2016 Infiniti QX60. 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 or P0306, first perform the trouble diagnosis for P0300, P0301, P0302, P0303, P0304, P0305, and P0306. Refer to  DTC LOGIC  . 

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 being stuck open.

DTC No. CONSULT screen terms
(Trouble diagnosis content)
DTC detecting condition Possible cause
P0128 THERMSTAT FNCTN
[Coolant thermostat (coolant temperature below thermostat regulating temperature)]
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