@Gary Ridenour I appreciate the helpful suggestions. However, I've been through about the whole gamut with this one. First, I learned too late my scan tool did not read ABS codes. Got one that does, wound up replacing the ABS Module, solved the "limp home" problem, then developed a new one, the current headache. I have erased the code dozens of times, just the one recurs all the time. Today I opened up the harness at the Oxygen Sensor, found 12 volts present when key on, as it should be, but when I removed the fuse indicated on wiring diagrams to be feeding the sensor, it did not remove power to it. Thus, the wiring is different from the diagrams, official ones from Ford for the 2004. Worse yet, pulling other fuses, I have not yet found where the sensor is receiving it's power from. Could be a scary problem. I suspect these harnesses are built by contracted suppliers, likely checked for function by Ford before installation, if all works, it's assumed they are wired properly. Even my color codes do not match on some conductors! Frank