DTC P0128: Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature) [08/2015 - 10/2016]: Description

WARNING: This page is about a different car, the 2018 Toyota Sequoia, 2017 Toyota Sequoia, and 2016 Toyota Sequoia. However, it is still accessible from the selected car via links, so may be relevant.

This DTC is stored when the Engine Coolant Temperature (ECT) does not reach 75°C (167°F) despite sufficient engine warm-up time having elapsed.

DTC No.	DTC Detection Condition	Trouble Area
P0128	Conditions (a), (b) and (c) met for 5 seconds (2 trip detection logic): (a) Cold start (b) Engine warmed up (c) ECT less than 75°C (167°F)	Thermostat Cooling system Engine coolant temperature sensor ECM