Patent ID: 8443779

Claim:
A failure diagnosis device for a boosting system, including an atmospheric pressure sensor for detecting atmospheric pressure and for outputting said detected atmospheric pressure as a first detection result, a boosting circuit for boosting an input voltage and for providing an output voltage, and a control unit for controlling said output voltage of said boosting circuit based on said first detection result, and mounted on a vehicle having an internal combustion engine, comprising: a physical amount sensor for detecting intake pressure of said internal combustion engine as a physical amount that changes in accordance with said atmospheric pressure and for outputting said detected physical amount as a second detection result; and a diagnosis unit for making a failure diagnosis of said atmospheric pressure sensor based on said first and second detection results; wherein said diagnosis unit determines a time period from a time point at which said internal combustion engine stops until diagnosis of said atmospheric pressure sensor is started, based on a state of operation of said internal combustion engine until said internal combustion engine stops.