from other wiki answers bank 1 is the passenger side, bank 2 is the drivers side under drivers seat, sensors one are the one before converters towars engine and sensors 2 are the ones behind (after converters) , you have to use a 22 millimeter wrench to remove, bank 2 sensor 2 is blue plug, bank 2 sensor one I believe is white or gray color... this is from previous experience, I am 99% sure, I still have my 1997 expedition with 190000 miles and still runs fine, I had only changed transmission and fuel pump and other minimal items due to normal wear and tear.... hope this helps. sometimes it is easier to have a special sensor socket like the mechanics which has a slit along side of it to slide over sensor while not damaging the wires and removing the sensor, it is sometimes easier to remove the front wheels to get to sensor 1...
Bank 2 is the drivers side of the engine Sensor 2 is in the exhaust after the catalytic converter ( downstream )
Bank 1 is the passenger side of the engine in your Ford Expedition Sensor 1 is in the exhaust system before the exhaust enters the catalytic converter ( upstream )
Lack of upstream heated oxygen sensor switch - sensor indicates rich - bank no. 2
On a 2000 Ford Expedition ( 4.6 and 5.4 ) Bank 2 is the drivers side of the engine Sensor 1 is close to the engine BEFORE the exhaust enters the catalytic converter
On a Ford Expedition , 5.4 and 4.6 Bank 2 is the drivers side of the engine Sensor 2 is in the exhaust AFTER the catalytic converter ( downstream sensor also called the catalyst monitor )
driver side bank 1 before cat
In a Ford Expedition : Bank 1 is the passenger side of the engine Sensor 1 would be close to the engine before the exhaust enters the catalytic converter ( upstream sensor )
Replace it. Sensor 2 is the one AFTER the catalytic converter.
Those are the oxygen sensors in the exhaust above the catalytic converters.
On my 1998 Ford Expedition XLT , There are 4 Oxygen sensors. 1 each in front of the Cats. and 1 each behing the cat. for a total of 4 Oxygen Sensors.
Disconnect the electrical connector, then unscrew the sensor. Installation is the reverse.
On a Ford Expedition ( 4.6 and 5.4 ) Bank 1 is the passenger side of the engine Sensor 1 would be close to the engine BEFORE the exhaust enters the catalytic converter Sensor 2 would be AFTER the exhaust has passed through the catalytic converter