Lexus Troubleshooting Questions? Ask a Lexus Expert
Sorry you are having issues with the Lexus hybrid, most of the time these cars are pretty stress free.
This vehicle has two separate cooling systems. One for the engine and the other for the hybrid system to cool the inverter. Both take the same kind of coolant.
The coolant tank you are describing that is empty is the engine side of the cooling system. The Most common and really only coolant leak I ever see on these cars is the engine water pump. Its one of the few items still ran off of a drive belt on a Hybrid car. Once the water pump leaks, and hits the drive belt, coolant can get sent every direction under the hood.
when you say you drove 2 miles before the light came on, was it the light telling you low coolant?
Please let me know what other questions you have!