Its a designed in fail-safe that will allow the motor to barely run when i senses a serious fault. Im not sure what triggers limp-home mode in the subaru's. Limp home mode in rx-7's will barely run the engine, its basically undriveable. Cant rev it, it just falls on its face. Though, it will idle.

 

I don't think that our cars have "Limp" mode...per say. If you get a mass casualty, the ECU flashes, but the car still runs the same. Some cars...like my Dodge Stratus, fall on thier faces in "limp mode" and won't allow you to rev them out of anything.

Andy