Manufactured by Jatco, partially owned and operated by Toyota, the Ford CVT (Continuously Variable Transmission) is one of those few emerging technologies that has far outperformed expectations. Like most Ford transmissions, this unit has been wisely outsourced to a specialised manufacturer, one which specialises in just these sort of power train solutions. This approach appears to bear fruit in the CVT, as most Ford mechanics report seeing far fewer CVTs in for service than standard geared types.
Part of the reason for this CVTs reliability is the fact that it is a chain-driven unit, very similar in design to those used by Porsche. Unlike cheaper belt-drive CVTs (originally designed for lawn tractors and golf carts), the chain-drive CVT cannot slip while transferring power, using a set of expanding and contracting gears to vary ratio. This makes Ford (Jatco) CVTs one of the best and strongest on the market, and is only rarely let down by those few components involved that are manufactured by Ford itself.
Electrical Sensor Issues
A CVT relies heavily on computers to function, and has very few mechanical redundancies engineered into its design. Failure of any associated sensor will result in transmission malfunction, and the most common of which to fail is the pedal-mounted position sensor. Since the Freestyle uses drive-by-wire technology, it relies on this sensor to tell the vehicle how hard you are applying the throttle. The transmission requires this information to function, and without it will simply refuse to move the vehicle.
Solid-state computers are among the most reliable machines on the planet, though some do fail from time to time. Even the best designed circuit board uses few tight tolerances, and tiny manufacturer defects can worsen exponentially over time, causing failure. One of the few "common" failures of CVT equipped Fords is in the transmission's control computer, which is covered under the vehicle's 36K mile warranty.
There are no real trends in terms of CVT mechanical failure. Since a CVT has fewer moving parts than a standard 6-speed automatic, there really aren't too many things that can go wrong. There are about even numbers of breakages reported for any one of the CVTs components across the board, meaning that these are more than likely manufacturing defects and not due to any inherent weaknesses in the design.
If you follow the manual's recommended service schedule, the Jatco CVT should outlive the engine. One of the few things one can do to break a CVT is drastically increasing engine power by installing a turbocharger, supercharger or nitrous. Even so, the CVT is good for about an extra 50ft. lb. of torque over what the stock engine can produce, but any more than that and you are guaranteed to need a ride home.