At a glance
What can fail
The fuel tank floor under the fuel sender unit is thinner than designed. It can deform, causing the sender float to jam against other tank components. This makes the fuel gauge display approximately one quarter tank when the tank is actually empty.
What the fix does
You'll receive two letters. The first recommends keeping fuel above half-tank. The second requests you bring your vehicle to a dealer to have the fuel sender unit replaced.
Summarized — see the official notice for exact wording, dates, and contacts.