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Home >> Lexus >> 2023 >> NX 250 AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 124 (Engine Control System - Diagnostic Codes (P0087-P012F)) >> 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 [03/2023 - 03/2024] >> Monitor Strategy

Monitor Strategy

WARNING: This page is about a different car, the 2025 Lexus NX 350, 2024 Lexus NX 350, 2023 Lexus NX 350, and 2022 Lexus NX 350. However, it is still accessible from the selected car via links, so may be relevant.
Related DTCs P0128: Coolant thermostat (jugement by simulated engine coolant temperature)
P0128: Coolant thermostat (jugement 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 (for mass air flow meter sub-assembly)
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 720 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