Fail-Safe System
WARNING: This page is about a different car, the 2008 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.
When malfunction has occurred in any system, there is possibility of engine trouble due to continuous control based on that system. In such a case, the fail-safe system either controls the system using the data (Standard values) recorded in the engine control module memory, or stops the engine.