A method of controlling a fuel system includes determining the opening of a pressure relief valve and initiating a reseat strategy for the valve. The fuel system comprises a source of high pressure fuel and a pressure relief valve having at least one inlet fluidly coupled to the source of high pressure fuel and at least one outlet. The pressure relief valve has a closed position and at least one open position in which fuel is able to pass from the inlet to the outlet. The method comprises the steps of continuously measuring the pressure of the fuel in the fuel source, determining whether the pressure relief valve is in an open position, and generating an open signal if it is determined that the pressure relief valve is in an open position.