Code P0128

JITHIN MATHEW

MEMBER
2004 TOYOTA HIGHLANDER
3.3L
V6
4WD
AUTOMATIC
197,800 MILES

I got this code while on the highway with the cruise control set at 60 MPH. The temperature gauge is staying at where it should be and I am getting heat inside the car and car is does not overheat or overcool. I checked the engine coolant level and it’s level one radiator and reservoir. I replaced the coolant temperature sensor and it was working until 1 week later. I will post the freeze frame data. It says the IAT is at 52 degrees Fahrenheit even though it was only 37 degrees outside.

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Sunday, February 2nd, 2020 AT 6:34 AM

1 Reply

AL514

MECHANIC
5,119 POSTS

Hello,

This code is for Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature). This means there is either a wiring issue with the coolant temperature sensor or the thermostat is partially sticking open, preventing the engine from getting up to full operating temperature. I would deal with the thermostat issue first and then see if you get any other codes after the fix.

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Sunday, February 2nd, 2020 AT 9:10 AM