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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Control System (2GR-FKS) - 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 [12/2019 - 10/2022] >> Typical Malfunction Thresholds

Typical Malfunction Thresholds

P0128: JUDGMENT BY SIMULATED ENGINE COOLANT TEMPERATURE

Duration that both of the following conditions are met 5 seconds or more
(a) Estimated engine coolant temperature 75°C (167°F) or higher
(b) Engine coolant temperature sensor output Less than 75°C (167°F)
P0128: JUDGMENT BY ENGINE COOLANT TEMPERATURE CHANGE AT HIGH VEHICLE SPEED

Malfunction counter 3 times or more
Malfunction counter is incremented when following conditions are met A and B
A. Average engine coolant temperature change (vary with current engine coolant temperature, estimated ambient air temperature, intake air mass and vehicle speed) Less than 0°C/sec (0°F/sec)
B. Engine coolant temperature is satisfied throughout this period Less than 75°C (167°F)