Hi Thanks for replying, have you seen this actual fault on one of these kia engines, sounds like you have seen it often even.
I have now pulled the front sensor and looked down on the cat from the top with a borescope
and it looks OK.
Ill have another look at fuel trims. I think i only saw bank 1 fuel trim and it looked good at all engine speeds
I know some vehicles use the post cat sensor for further fueling corrections.
The rear sensor is just below the manifold cat
then after the flexi there is what kia are telling me is another cat. it does look like one but why would it be after the rear sensor.
There are after market cats available still 500 quid for both though.