My 2007 Escape Hybrid engine light came on and I went to get a free diagnostic scan at a local garage, and the reading came out P0128. The Escape warms up fine and I have heat in the cold weather. What do you guys think does the sensor or thermostat needs to be replace? Or maybe both? Regards and Thanks you.

 

Since no one replied I figured it out myself. It was the thermostat that was bad, and not the sensor. I went to several garages and they all gave me a price above $380 to change the thermostat. Several garages were trying to take advantage of me thinking I don't know what was wrong and told me I have to change both the sensor and thermostat and would charge close to $500.00. I ended up taking to a friend of my brother and paid him $85 since he has tools and I bought the thermostat for $66.00 and coolant for $13.00 at a Ford dealership. Now the p0128 code is gone.

 

My answer would have been the sensor given your description of its actual performance. However, some ECUs are very sensitive to changes that might go unnoticed by the feel. I'm glad you got it sorted, but I would recommend replacing the sensor as well.

 

Can you go farther on why you recommend changing the sensor, when I look under the hood, and took a look at the sensor it seems clean. The part is not that expensive, and it seems like a DIY from watching the YOUTUBE video.

 

Sensors fail and are generally inexpensive. As components age, they are more likely to fail. With the thermostat replaced, of the two, your sensor is the more likely component to fail next. You can always keep the older (and apparently working) unit as a test piece should you have another P0128 code.

 

Don't know how the FE I4 compares to the FEH but there was a post in another forum from a Ford Tech. The CT is calculated from the cylinder head temperature sensor. The sensor sets in a pocket which has a drain hole for water, etc. which gets plugged with dirt, etc. which ends up corroding the sensor and connector. Ford even sells a connector pigtail, you just cut the old one off and splice in the new one. You'll need a deep well socket for the sensor. IIRC, Ford issued a SSM or TSB on this.