Porosity in the engine castings may result in cracks than can allow coolant to leak internally and/or externally.
A coolant leak can cause the engine to overheat and cause a vehicle stall in conventional gasoline vehicles, increasing the risk of a crash.
Additionally, for all involved vehicles, the engine may suffer damage mechanically, possibly resulting in an engine oil leak, increasing the risk of a fire.
What to do
Toyota will notify owners, and dealers will inspect and replace the engine including the engine block -- as necessary -- free of charge. The recall is expected to begin April 6, 2020.
Owners may contact Toyota customer service at (888) 270-9371 or Lexus at (800) 255-3987. Toyota's number for this recall is 20TA04. Lexus' number for this recall is 20LA02.