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Q: Code p0128

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I have been having an issue with my check engine light sense i bought it. Its throwing code p0128, coolant not getting up to temp. One garage told me it was the thermostat and they replaced it. Another told me it was the cylinder head temp sensor and replaced it. Still getting the code. No idea what it could be. Someone told me it might be the coolant temp sensor but i get a good reading from my scan guage when im driving. On the highway it sits right at 173-175 and doesnt move. If i stop the vehicle and its just sitting idling its gets around 210.

My car has 140000 miles.
My car has an automatic transmission.

Code P0128 is engaged specifically when the engine itself does not get to operating temperature in a specified time period. The only things that can cause this problem is an issue with the thermostat, head temp sensor, and the coolant sensor.

You have replaced the first two, so you should replace the coolant temperature sensor next to see if another sensor may be more sensitive to temperature changes and fix the problem.

If you decide to get this fixed, consider YourMechanic, as a certified technician can come to the vehicles location to accurately diagnose your trouble code in person and suggest an accurate fix. Good luck.

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