Patent ID: 7275525

Claim:
A control apparatus for an internal combustion engine comprising: a throttle valve that is opened and closed in an intake pipe for adjusting an amount of air supplied to said engine through said intake pipe; a bypass air amount control section that controls an amount of bypass air flowing while bypassing said throttle valve; an EGR tube that recirculates an exhaust gas exhausted from said engine into said intake pipe at a location downstream of said throttle valve; an EGR valve that adjusts a flow rate of EGR of said exhaust gas flowing through said EGR tube; a sensor part that detects an operating condition of said engine including an intake pipe pressure in said intake pipe and the number of revolutions per minute of said engine; an EGR control section that controls said EGR valve in accordance with operating condition information from said sensor part; a failure determination condition detection section that detects, based on said operating condition information, whether a failure determination condition for said EGR control section is satisfied; an EGR valve forced opening and closing section that forcedly opens and closes said EGR valve based on said operating condition information when said failure determination condition is satisfied; and a failure determining section that determines whether said EGR control section is in failure, by comparing a pressure change index value based on said intake pipe pressure at the time of the forced opening and closing of said EGR valve with a failure determination value; wherein said failure determination condition detection section includes an intake pipe pressure adjustment section that adjusts said intake pipe pressure so as to be within a predetermined range by using said bypass air amount control section; and said failure determination condition detection section detects, as a satisfied state of said failure determination condition, that said intake pipe pressure is within said predetermined range.