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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 52 (Engine Control System (A25A-FXS) - Diagnostic Codes (P0128-P0171)) >> 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 [10/2022 - 11/2023] >> Monitor Strategy

Monitor Strategy

WARNING: This page is about a different variant/trim than selected.
Related DTCs P0128: Coolant thermostat (judgment by simulated engine coolant temperature)
P0128: Coolant thermostat (judgment by engine coolant temperature and No. 2 engine coolant temperature changes)
Required Sensors/Components (Main) Thermostat
Engine coolant temperature sensor
Required Sensors/Components (Related) Intake air temperature sensor
No. 2 engine coolant temperature sensor
Frequency of Operation Once per driving cycle
Duration 90 seconds: Judgment by simulated engine coolant temperature
-: Judgment by engine coolant temperature and No. 2 engine coolant temperature changes
MIL Operation 2 driving cycles
Sequence of Operation None
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