are pre cat and post cat lambda's interchangable
think my pre cat lambda may be on its way out and got a brand new post cat sensor here. could i fit it and see if it works. sensors are identical bar ones a blue plug and others a green plug.
cars a focus rs mk1

 

both 4 wire sensors? 1xblack 1xgrey 2xwhire wires? I would say yes.

If the plugs will connect and if the wiring is long enough, some cars have same wiring/plugs on both sensors.

For the cost though I would just replace with a new item.

 

You will most likely find the muti plugs are different and that the ohm's resistance is different over the heater circuits

 

Their the same on the ka's,interchanged them loads of times and had no issues.

 

the plugs are the same except ones blue and ones green. the thread for plug is the same. im going to try it anyway and see if it makes a difference,then if it does ill order a new lambda from matt lewis