Fault diagnosis device

A fault diagnosis device determining whether a fault occurs in an evaporative-gas purge pipe which is provided to an internal combustion engine with a supercharger, the evaporative-gas purge pipe including a first purge pipe through which an evaporative-gas generated in a fuel tank flows into an intake pipe downstream of a compressor, and a second purge pipe through which the evaporative-gas flows into the intake pipe upstream of the compressor, the intake pipe supplying an air to the internal combustion engine, the fault diagnosis device comprising:

• a first open/close valve provided to the first purge pipe;
• a second open/close valve provided to the second purge pipe;
• a pressure reduction pump reducing both of a pressure in the first purge pipe between the first open/close valve and the fuel tank and a pressure in the second purge pipe between the second open/close valve and the fuel tank;
• an obtaining portion obtaining a flow rate information relating to a flow rate of an air flowing into the second purge pipe from the intake pipe;
• and
• a control unit controlling an operation of whole of the fault diagnosis device, wherein
• when the internal combustion engine is stopped, the pressure reduction pump performs a pressure reduction while the first open/close valve and the second open/close valve are closed,
• subsequently, the control unit determines whether a fault occurs in the second purge pipe between the second open/close valve and the intake pipe based on the flow rate information which is obtained immediately after the second open/close valve is opened, and
• the obtaining portion is located upstream of the compressor inside the intake pipe.