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About a week ago my 2015 TC started struggling to start. It would crank a few seconds before actually starting. It seemed that each day it got a little worse. I also noticed that my fuel economy took a dump during that time as well. Additionally, when it would crank prior to starting I noticed the strong smell of unburned fuel in the garage. That's never a good sign. Yesterday, it cranked for about 15 seconds (a long time for any fuel injected vehicle to crank and not fire up) before it finally started. Once started, it didn't immediately respond to throttle input and it seemed to be searching for the correct engine RPM. After a minute it settled down and appeared ok to drive (throttle response returned). It was then that I drove it directly to my local repair shop who theorized that it was the engine temp sensor. Upon completion of their diagnostics, they found that my engine temp sensor was reading 117 degrees below zero. The implication is that it was telling the computer to dump more fuel into the engine to compensate for the extremely cold temperatures it was sensing. Obviously, the sensor was bad because it was clearly NOT 117 below zero outside. As such, one hour and $143.00 later it was fixed. (I felt $143.00 is a bit high for a repair of this type, but I needed to get back on the road ASAP and wasn't gonna squabble over the $50.00 I felt I should have saved!) It may be worth noting that the temp sensor is mounted in the head and doesn’t measure coolant temperature, but simply the temperature of the cylinder head itself. This is unusual in my experience, and explains why the dash temp gauge was already in the 'normal' range at only a quarter mile from my house each day (coolant simply doesn't heat up that fast -but cylinder heads do). Additionally, I suspect the throttle response got better when I started it earlier because -as the cylinder head heated up (the sensor is mounted in the cylinder head right between plug 2 & 3) the sensor started reading the combustion heat in the head and allowed more throttle input once the motor warmed up. It runs like normal now, and my otherwise great fuel economy has returned. The Ford part number for this temp sensor is: 8S4Z-6G004-A and can be found at most ANY ford dealership. They run about $53.00USD. I hope that some find this information helpful. Ken