On a 1997 Ford Expedition , 5.4 liter V8 :
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 in a Ford Expedition Sensor 2 is after the catalytic converter ( downstream )
On a 1997 Ford E-150 : Bank 1 is the passenger side of the engine ( V6 and V8 ) Sensor 1 would be close to the engine BEFORE the exhaust enters the catalytic converter
Bank 1 is the passenger side of the engine ( 4.2 / 4.6 / 5.4 ) in your 1997 Ford F-150 Sensor 1 is in the exhaust ( close to the motor ) before the exhaust enters the catalytic converter
Bank 2 is the drivers side of your V6 or V8 engine in a 1997 Ford F-150
On your 1997 Ford Thunderbird , 3.8 liter V6 : Bank 1 is the passenger side of the engine Sensor 2 would be AFTER the exhaust has passed through the catalytic converter
Bank 2 is the drivers side of the engine in your Ford Explorer Sensor 1 is in the exhaust , close to the engine , before the catalytic converter ( upstream sensor )
Bank 1 sensor 3 should be the one after the catalytic converter.
P0153....O2 Sensor Circuit Slow Response (Bank 2 Sensor 1)
Bank 1 is the passenger side of the engine in your 1997 Ford Explorer ( V6 engines and V8 engine ) Sensor 1 is before ( upstream ) the exhaust enters the catalytic converter Sensor 2 is after ( downstream ) the exhaust leaves the catalytic converter
Bank 2 is the drivers side of the engine in your Ford Explorer Sensor 1 would be somewhere in the exhaust , close to the engine , before the catalytic converter
usually bank 1 is the bank with # 1 cylinder in it and sensor # 1 is the front o2 sensor(usually in the manifold). You will need a O2 sensor socket or a 22mm wrench or deep socket.
Bank 2 is the drivers side of the engine in your Ford Crown Victoria Sensor 2 would be in the exhaust after the catalytic converter ( downstream )