The sensors are consumables meaning replacement.


The front sensor is accessible. The rear (Bank 2) is buried. Ford shop manual says to remove and that's it. I can see the green plug wire but not the sensor.

Is the Bank 2 sensor accessible from underneath the car?Or does the Uppper Intake Manifold require removal?

 

The answer is that the upper air intake manifold must be removed to gain access to the Bank 2 Upstream O2 sensor. Should be replaced when plugs are replaced at 100k. RockAuto BoshOEM for $38 each.Of the four, the Upstreams are most important.