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Home >> Lexus >> 2024 >> TX 350 Base, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 39 (Engine Control System - Diagnostic Codes (2 Of 6)) >> SFI System >> DTC P0128-00: Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature); DTC P0128-07: Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature) Mechanical Failure [12/2023 - ] >> Monitor Strategy

Monitor Strategy

WARNING: This page is about a different car, the 2024 Lexus TX 550h+. However, it is still accessible from the selected car via links, so may be relevant.
Related DTCs P0128: Coolant thermostat (judgment by simulated engine coolant temperature)
P0128: Coolant thermostat (judgment by engine coolant temperature change at high vehicle speed)
Required Sensors/Components (Main) Thermostat
Engine coolant temperature sensor
Required Sensors/Components (Related) Intake air temperature sensor
Vehicle speed sensor
Frequency of Operation Once per driving cycle: Judgment by simulated engine coolant temperature
Continuous: Judgment by engine coolant temperature change at high vehicle speed
Duration 280 seconds: Judgment by simulated engine coolant temperature
-: Judgment by engine coolant temperature change at high vehicle speed
MIL Operation 2 driving cycles
Sequence of Operation None