Failure diagnostic method and apparatus for manifold pressure sensor

Abstract

To identify a failed manifold pressure sensor in a control apparatus having two manifold pressure detection systems as a. A calculating unit calculates a difference between the manifold pressure detected by two sensors. A first comparing unit outputs an abnormal signal when the difference is larger than a threshold value. A calculating unit calculates a difference between the manifold pressure and the atmospheric pressure. A difference calculating unit calculates a difference between the manifold pressure and the atmospheric pressure. When the abnormal signal is outputted from the first comparing unit while an engine is stopped, a second comparing unit compares the differences in response thereto. Depending on which one of the differences is larger, it is determined which one of the manifold pressure sensors is abnormal.