A method of managing faults for a vehicle engine control system, includes a plurality of monitoring or observation strategies monitoring a plurality of components and using diagnostics to detect the presence of faults in the plurality of components. For each monitoring or observation strategy, referred to as a diagnosis, if it diagnoses the presence of a fault in a component, the fault detected in the diagnosed component is stored and all the monitoring or observation strategies continue to detect the presence of faults in all of the components that they respectively monitor, but the presence of the fault in the diagnosed component is ignored so as to enable the detection of the presence of other faults, if any, in components other than the diagnosed component.