Method of detecting abnormality in pressure sensor and fuel cell system

A method of detecting an abnormality in a pressure sensor of a fuel cell system including a fuel supply flow passage configured to connect a fuel cell and a fuel supply source, a first pressure sensor provided in the fuel supply flow passage, a second pressure sensor provided on a downstream side of the fuel supply flow passage from the first pressure sensor, a pressure reducing valve provided between the first pressure sensor and the second pressure sensor in the fuel supply flow passage and configured to decrease a pressure on an upstream side to a predetermined pressure regulation lower limit value, a first shutoff valve provided between the fuel supply source and the first pressure sensor in the fuel supply flow passage, and a second shutoff valve provided between the second pressure sensor and the fuel cell in the fuel supply flow passage, the method comprising:

• closing the first shutoff valve to shut off supply of fuel from the fuel supply source to the first pressure sensor;
• after shutting off the supply of fuel from the fuel supply source to the first pressure sensor, opening the second shutoff valve and allowing fuel in the fuel supply flow passage to be supplied to the fuel cell to decrease a pressure on an upstream side and a pressure on a downstream side of the pressure reducing valve to be equal to or less than the pressure regulation lower limit value;
• and
• after decreasing the pressure on the upstream side and the pressure on the downstream side of the pressure reducing valve to be equal to or less than the pressure regulation lower limit value, closing the second shutoff valve and comparing detection pressure values of the first pressure sensor and the second pressure sensor with each other to determine whether or not the first pressure sensor or the second pressure sensor is abnormal.