Patent ID: 7243021

Claim:
A failure diagnostic apparatus for manifold pressure sensors used in an engine control system having a first manifold pressure sensor that performs main control, a second manifold pressure sensor that backs up the first manifold pressure sensor, and an atmospheric pressure sensor, comprising: an engine stoppage detection unit that detects a fact that an engine is stopped; an abnormality recognizing unit that outputs an abnormal signal when the difference between a first detected manifold pressure value detected by the first manifold pressure sensor and a second detected manifold pressure value detected by the second manifold pressure sensor exceeds a threshold value; and an abnormality identifying unit that calculates the differences between the first detected manifold pressure value and the second detected manifold pressure value with respect to the pressure value detected by the atmospheric pressure sensor, respectively, and identifies as a failed sensor the manifold pressure sensor that detects the manifold pressure value having a calculated difference that is larger, wherein identification of the failed sensor by the abnormality identifying unit is performed in response to an output of the abnormal signal while the engine is stopped.