Purchased my 07 Fusion 2.3i4 with 95k about. Within the first week of ownership, I noticed that on the dash the engine coolant temperature gauge was not reaching its normal zone. Normal meaning about half way.

Then another week or two went by before I decided to spend $200 on a OBD 2 scanner to see the engine coolant temp in real time. So the only test I did with the scanner was drive to a desired destination (work, across town), and see the coolant temp in real time. There is a zone for the engine coolant temp (I forget, its been almost a year), and the number I saw was lower than the desired zone specified.

This diagnosis was easy, which pointed to a poor performing "engine coolant thermostat".

With this evidence, I then realized that the vehicle had "Powertrain Warranty" as listed on the purchase agreement. So I called the dealer back, explained what I did, and arranged a time to bring the vehicle back to have the thermostat replaced.

The day I got the vehicle back, on the drive home, I noticed the MPG on the dash display go up from 15 to 22 over a 30 min drive.

Before I brought the car back to the dealer, I was thinking that having replaced a thermostat on a 03' expedition, I thought this might be easy as well. NOT TRUE. I obtained step by step material, and examined the thermostat location under the hood and realized it was not an easy DIY project.

In July 2016, I found a youtube video on how to replace the thermostat, and watched parts of it. It's not an easy fix, is it a possible DIY project, maybe? IDK. Here's a link to that video.

Overall, I wasn't too upset of this. Just annoying