The exhaust temperature sensor should be under powertrain warranty. While the document I have linked below is in Kilometers, your owner's manual should have the same basic wording.
http://www.fordservicecontent.com/Ford_C...-US_01_2014.pdf
Quote:
F-Super Duty Equipped with a 6.7L Diesel Engine Unique Powertrain Coverage
Under the New Vehicle Limited Warranty, the following components are covered against defects in factory-supplied materials or workmanship for 5 years or 160,000 kilometres (whichever occurs first) from the original warranty start date.
Transmission - All internal parts; clutch cover; seals and gaskets; torque converter; transfer case (including internal parts); transmission case; transmission mounts.
Four-Wheel Drive - Axle shafts; front-wheel bearings; rear-wheel bearings; centre support bearing; drive shafts; hubs-automatic front locking; locking rings; seals and gaskets; constant velocity and universal joints.
Rear-Wheel Drive - Axle shafts; front-wheel bearings; rear-wheel bearings; centre support bearing; drive axle housing and all internal parts; drive shaft; propeller shafts; retainers; supports; seals and gaskets; universal and constant velocity joints.
6.7L Diesel Engine Coverage
The New Vehicle Limited Warranty covers certain Direct Injection Diesel Engine components against defects in factory-supplied materials or workmanship for 5 years or 160,000 kilometres (whichever occurs
first) from the original warranty start date.
Covered components: cylinder block, heads and all internal parts, intake and exhaust manifolds, timing gear, harmonic balancer, valve covers, oil pan and pump, water pump, fuel system (excluding fuel lines, fuel tank, and frame mounted fuel conditioning module sometimes referred to as the frame mounted pump/filter/water separator or frame mounted fuel filter/water separator), high pressure lines, gaskets and seals, glow plugs, turbocharger, two-stage turbocharger assembly, turbocharger actuator, powertrain
control module, high pressure fuel injection pump assembly, injectors, injection pressure sensor, fuel rail pressure sensor, exhaust back pressure regulator and sensor, exhaust pressure sensor, manifold pressure sensor, intake air temperature sensor, crankshaft position sensor, camshaft position sensor, engine mount
exhaust gas temperature (EGT) sensor, accelerator switch.