Hi just looking for some advice I have a 2011 skoda octavia 1.6 mpi came up with bank one below threshold so changed o2 sensor dove for a bout 80 miles and it came up with same problem but this time car wont idle after it heats up revs drop but fine wen on motorway 

I think there may well be two sensors an upstream and downstream one.  The upstream one is likely more expensive and harder to get to.

 

Are you sure it is not related to any related other issues first. i.e. diagnostic codes do not always tell you which part is faulty they point you in the direction but could just point the finger at some sensor that is out of tolerance because of a related issue...

 

Edit: maybe not harder to get to on an MPI (no turbo to get in way).  Have a look at back of engine on exhaust manifiold. Removal and clean is another possibility.  

Edited 13 November, 20196 yr by TheClient

Hi thsts the sensor thsts been changed but they are saying it could be the catalytic converter but car runs fine wen u get up the revs