Where is the ford fiesta o2 sensor bank 1 located?

The Ford Fiesta's Bank 1 O2 sensor should be found before the catalytic converter and near engine cylinder #1. Additional sensors should be installed after the catalytic converter. They form a valuable link in a vehicle's emission and ignition systems by monitoring the amount of unburnt oxygen exiting the exhaust pipes. This data is sent to the car's main computer or ECU and used to inform the engine's air/fuELRatio. When working, an O2 sensor helps to maintain optimal fuel economy and firing. When sensors start to fail or become d***y, readings will be compromised, causing the car to run too "rich" or too "lean" and can result in rough idling, reduced gas mileage and mIS Fires. Cost of replacing an O2 sensor in a Ford Fiesta averages $170-$180 in parts and labor.