Bank # 1 is the passenger side of the engine in a Ford Expedition
Sensor # 1 would be before the catalytic converter ( upstream sensor )
Sensor # 2 would be after the catalytic converter ( downstream sensor )
Bank 2 is the drivers side of the engine in a Ford Expedition Sensor 2 is after the catalytic converter ( downstream )
Bank 2 is the drivers side of the engine in your Ford Expedition Sensor 1 is in the exhaust BEFORE it enters the catalytic converter ( upstream )
Bank 1 is the passenger side of the engine in your Ford Expedition Sensor 1 is in the exhaust before it enters the catalytic converter ( upstream )
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 )
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
Bank 2 is the drivers side of the engine in a Ford Expedition Sensor 1 would be in the exhaust close to the engine before the exhaust enters the catalytic converter ( upstream )
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 )
Bank 1 is the passenger side of the engine in your Ford Expedition Sensor 2 is after the catalytic converter ( downstream )
On a 1997 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
Bank 2 is the drivers side of the engine Sensor 2 is in the exhaust after the catalytic converter ( downstream )
Bank 2 is the drivers side of the engine Sensor 2 is in the exhaust pipe after ( downstream ) the catalytic converter
Lack of upstream heated oxygen sensor switch - sensor indicates rich - bank no. 2