My backup sensors have taken to working "sometimes", " sometimes not" I took it to the Ford garage to install a remote starter and to fix the sensors. They tell me that my expedition does NOT have them. They can't locate them on the back bumper. I KNOW I DO HAVE THEM,,,I'VE HEARD THEM FOR SEVERAL YEARS. Where are they?

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.

Marvin

• 85242 Answers
• Posted on Oct 14, 2008

SOURCE: relay

There are 2 relays or solenoids as they called on a starter, one is on the inside of the fender under the hood, follow the positive battery cable, the other is on the starter, both do the same thing, later years only have the one solenoid on the starter.

SOURCE: where is located ford expedition 1999 starter relay

on the firewall behind the battery

SOURCE: 1999 FORD EXPEDITION VEHICLE SPEED SENSOR

It should be on the back of the transmission near where the driveshaft goes in. Buy a new one, jack up your truck and look for the old one on the back of the transmission

SOURCE: Ford backup sensors not working

I would buy a Chilton Repair Manual from a local parts store and a digital ohm meter. If the chilton doesn't have the ohms for all the sensors then research online for the specs on the sensor. It sound like a wiring issue or relay.