At a glance
What can fail
The engine block heater cable lacks sufficient heat protection and may be damaged by high temperatures, causing it to short circuit when plugged in and overheat or melt the wiring.
What the fix does
Stop using the block heater immediately. Toyota will mail instructions to take your vehicle to a dealer to disable it. A replacement heater or refund will be provided.
Summarized — see the official notice for exact wording, dates, and contacts.