Fail-safe device for electronic throttle control system

A fail-safe device for an electronic throttle control system comprising:

• an intake air amount sensor for detecting an intake air amount to an engine;
• a throttle position sensor for detecting a throttle opening degree of an electronic throttle controller, said electronic throttle controller controlling a throttle valve based on an amount of pressing down on an accelerator;
• an accelerator position sensor for detecting an accelerator opening degree as an amount of pressing down on said accelerator;
• an intake air amount control means for controlling the intake air amount to said engine;
• a target air-fuel ratio control means for controlling a fuel injection amount to be supplied to said engine;
• a target ignition timing control means for controlling ignition timing of air-fuel mixture inside a cylinder of said engine;
• and
• an electronic throttle control system abnormality warning means for deciding, when a first requirement and a second requirement are satisfied based on the output of said intake air amount sensor, said throttle position sensor, and said accelerator position sensor, that said electronic throttle controller is in failure, and prior to warning of the abnormality of said electronic throttle controller, controlling said intake air amount control means, said target air-fuel ratio control means, and said target ignition timing control means.