Heated Oxygen Sensor
WARNING: This page is about a different car, the 2002 Ford Pickup and 2002 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
Faults in Heated Oxygen Sensor (HO2S) or circuit should set a Diagnostic Trouble Code (DTC). Perform TEST H: FUEL CONTROL in SELF-DIAGNOSTICS - EEC-V - BI-FUEL article.