I have a 2006 Ford Expedition (Eddie Bauer edition). I love the car, but three times now it has just shut off at random while driving it. I receive a Engine Failsafe Mode message and the Check engine light comes on momentarily. All three times the speed was under 25 mph thankfully so I was able to coast into a spot away from traffic, but I won't drive the car again until I know it's been fixed. The problem is that of the three mechanics who've driven and checked out the car (including Ford), no one has been able to find anything. There have been no codes, and nothing to indicate that there is anything wrong. Since no one can figure this out, I'm at the point where I'll be trading my car in on either another (later) year or something other than a Ford.

SOURCE: Oxygen Sensor Location 2001 Ford Expedition Eddie Bauer

There are four o2 sensors on this truck. one on each side just below the exhaust manifold, and one on each side behind the second catalytic converters. (just about even with the back of the front doors.

SOURCE: diagram bypass heater cord on 2001 ford expedition eddie bauer

the heater bypass is quite simple, if you look at the firewall you will see two medium sized coolant lines, remove them from the firewall and link them together using a proper sized tube, you can purchase a kit at a parts store quite cheaply

SOURCE: Enigine fail safe mode

Sounds to me like the mass airflow meter, cutting in and out. When faulty it can completely shut a car off, and also ingauge limp mode. I hope this helps. Let me know how you get on.

SOURCE: 06 Expedition Engine fail safe mode

truck needs to be scanned for the codes,most major parts stores will do this for little or no charge,get back to me with the codes and we'll go from there

SOURCE: location of air conditioner low pressure valve

The low pressure valve on the 01 expedition is located on the accumulator on the passenger side fire wall. The accumulator is underneath the battery relay and a grouping of wires. Had to squeeze hand underneath a heater hose and an a/c line to remove cap and hook up hose. Nothing has to be removed to locate the valve just a little touchy feely. Valve faces a 45 forward toward the engine.