A fuel cell system comprising a controller, a temperature sensor that has a physical presence in a conduit within the system to measure the temperature of the fluid at a point within the conduit (Tg) and a wall temperature sensor for sensing a temperature of a wall of the conduit (Tw). The controller takes Tg and Tw as inputs and applies an equation with known constants to calculate measurement error of Tg based on the local flow temperature and geometry and arrives at a calculated temperature. The equation may be applied iteratively until the difference between the calculated temperature and Tg is below an acceptable value when the calculated temperature can then be assumed to be an accurate representation of the actual gas temperature at the Tg measurement point. The direction of calculation is controlled by the relative difference between Tg and Tw.