Diagnostic system and method for processing continuous and intermittent faults

A method for diagnosing a device in a vehicle control system during a plurality of diagnostic tests, comprising:

• selecting one of a normal control mode, a temporary default action mode and a permanent default action mode for the vehicle based on the plurality of the diagnostic tests;
• using a diagnostic module, tracking a first number of successive test samples of the device, a second number of failed samples that occur during the successive test samples of the device, a third number of successive failed samples of the device, a fourth number of accumulated failed samples of the device, and a fifth number of samples since a last failed sample of the device;
• transitioning from the normal control mode of the vehicle to the temporary default action mode of the vehicle and taking a temporary default action when at least one of the third number of successive failed samples is greater than a first value and the fourth number of accumulated failed samples is greater than a second value;
• and
• transitioning to the permanent default action mode of the vehicle and taking a permanent default action that is different than the temporary default action when the second number of failed samples is greater than a third value.