Method and system for diagnosing failure of temperature sensor for fuel cell

1. A method for diagnosing a failure of a temperature sensor for a fuel cell, comprising:

measuring a temperature of an outdoor air of a vehicle wherein the temperature of the outdoor air is within a predetermined temperature range, is determined to diagnose the failure of the temperature sensor by using the temperature of the outside air;

calculating, by a controller, a heating value generated at a fuel cell stack during a predetermined diagnosis time;

calculating, by the controller, a temperature variation of the fuel cell stack from the calculated heating value; and

diagnosing, by the controller, the failure of the temperature sensor configured to measure a temperature of the fuel cell stack based on the calculated temperature variation of the fuel cell stack,

wherein the calculating of the heating value of the fuel cell stack includes:

calculating, by the controller, an amount of power of the fuel cell stack during the predetermined diagnosis time; and

calculating, by the controller, the heating value of the fuel cell stack using a relationship between the amount of power of the fuel cell stack and the heating value thereof, and

wherein the amount of power of the fuel cell stack is calculated by multiplying a power consumption of a drive motor connected to the fuel cell stack by a weighting factor during the predetermined diagnosis time to account for at least one of a high voltage battery or an auxiliary power source;

wherein the calculating of the temperature variation of the fuel cell stack includes:

calculating, by the controller, the temperature variation of the fuel cell stack from the calculated heating value of the fuel cell stack using predetermined heat capacity of the fuel cell stack.

2. The method of claim 1 , further comprising:

before calculating the heating value of the fuel cell stack, determining, by the controller, whether an initial temperature of the fuel cell stack is able to be assumed as the temperature of the outdoor air,

wherein, when the initial temperature of the fuel cell stack is able to be assumed as the temperature of the outdoor air, the calculating of the temperature variation of the fuel cell stack includes assuming the temperature of the outdoor air as the initial temperature of the fuel cell stack and calculating the temperature variation of the fuel cell stack.

3. The method of claim 2 , wherein the determining of whether the initial temperature of the fuel cell stack is able to be assumed as the temperature of the outdoor air includes determining whether the fuel cell stack is re-operated after an operation of the fuel cell stack is stopped for a predetermined stop time or longer.

4. The method of claim 1 , wherein the calculating of the heating value of the fuel cell stack includes:

measuring, by the controller, an output voltage and an output current of the fuel cell stack during the predetermined diagnosis time; and

calculating, by the controller, the heating value of the fuel cell stack based on the measured output voltage and the measured output current.

5. The method of claim 1 , wherein the diagnosing of the failure of the temperature sensor includes:

comparing, by the controller, the calculated temperature variation of the fuel cell stack with a temperature variation measured at the temperature sensor during the predetermined diagnosis time; and

diagnosing, by the controller, the temperature sensor as failing when the comparison result is equal to or greater than a predetermined reference value.