Alcohol sensor failure detection system for internal combustion engine

Claim 1

An alcohol sensor failure detection system for an internal combustion engine, comprising: air/fuel mixture induction means for receiving an intake air and a fuel to form an air/fuel mixture to be fed into an engine combustion chamber; fuel supply means for supplying a controlled amount of the fuel into said induction means; an alcohol sensor associated with said fuel supply means for producing a first signal indicative of alcohol concentration contained in the fuel to be fed into said induction means from said fuel supply means; sensor means for producing a second signal indicative of an air/fuel ratio of the air/fuel mixture; first means for deriving a first amount of the fuel to be fed into said induction means from said fuel supply means, said first amount derived based on said first signal and predetermined other signals indicative of respective engine operating conditions; second means for deriving a correction coefficient variable between predetermined maximum and minimum values depending on said second signal, said correction coefficient being derived through a FEEDBACK control which is executed in a predetermined engine driving range such that the air/fuel ratio of the air/fuel mixture is maintained at a target value in said predetermined engine operating range with a second amount of the fuel derived by third means which corrects said first amount with said correction coefficient, said second amount of the fuel being fed into said induction means from said fuel supply means; fourth means for determining whether said FEEDBACK control is executed; fifth means, in response to a positive decision of said fourth means, for determining whether said correction coefficient is said predetermined maximum or minimum value; sixth means, in respone to a positive decision of said fifth means, for measuring a time in which said correction coeffient is retained to said predetermined maximum or minimum value; seventh means for determining a failure of the alcohol sensor when said measured time is no less than a predetermined value.