Lambda Sensors

[driverles]

Hi could any one give any info on the following

I am looking at replacing the Cat & 2 lambda sensors on my Fusion the problem is looking at different parts sites I've now got confused as I understand that the pre - cat sensor is a regulating & the post - cat sensor is a diagnostic one, Some sites tell you which is which and one is a bit dearer than the other but I have also found a site that lists one as being pre & post cat, I have also been told that the 2 sensors are identical although they do different things and that this is the case on my car. I tried contacting my local Ford dealer although they said the parts were the same price they could not or would not tell me if they were the same part, can anyone tell are the 2 the same or not

Thanks in advance for any help

Les

[iantt]

Same sensors, only difference is length of wires and multiplug.

[driverles]

Thanks Ian