Control method

A fuel system for an engine including:

• at least one fuel injector;
• a source of fuel at high pressure for delivering fuel to the injector;
• a pressure sensor arranged to provide an output signal indicative of the pressure of fuel delivered to the injector;
• a metering valve arrangement including a valve member which is movable through a range of operating positions to vary the rate of flow of fuel to the source and, hence, the pressure of fuel to be delivered to the injector;
• a control arrangement for controlling a current supplied to the metering valve arrangement;
• a speed sensor for measuring the speed of the engine;
• and
• a monitor for monitoring the status of the pressure sensor so as to determine whether a fault condition has occurred within the pressure sensor, wherein the control arrangement is arranged to vary the control current supplied to the metering valve arrangement in response to the measured engine speed so as to maintain engine operation at a substantially constant engine speed in the event that a fault condition is detected by the monitor.