Hard Faults
WARNING: This page is about a different car, the 2002 Mercury Villager. However, it is still accessible from the selected car via links, so may be relevant.
Hard faults may cause CHECK ENGINE or MIL to illuminate and remain illuminated until fault is repaired. If MIL illuminates and remains on or flashes during vehicle operation, cause of malfunction must be determined. Retrieve all DTCs. If DTCs are retrieved during QUICK TEST, see DIAGNOSTIC TROUBLE CODE DEFINITIONS to find appropriate system test to perform. See QUICK TEST . If a sensor fails, PCM will use a substitute value in its calculations to continue engine operation. For additional information, see FAILURE MODE EFFECTS MANAGEMENT . In this condition, vehicle is functional, but driveability will be affected.