Is this the first 02 or the second as it just has bank one, but from what I can tell is there both bank one just 1 & 2.

Was going to change these first as cheap cheers matt

Sorry, your post isn't making any sense at all??????

Hi I'm sorry will explain better, Im getting code po420 which is 02 bank 1 out of working range, was just wondering if this is the pre cat 02 or post, as it only said bank one not S1 or s2'

Dose this make sense?

Sounds like an imbalance between the Lambada sensors meaning it is out of percentage range.

Catalyst could be on the way out.

However I had a 2 liter MK1 estate that would throw up this code randomly and still passed the emissions for the MOT for 5 years in a row even having changed the Lambada sensors.

I cancelled the code with a cheap reader and put Redex in at every fill and avoided cheap fuel by using Shell.

I have a MK 2 hatch that is doing the same so will carry on until it fails the MOT then change the catalyst. 

Hi Jong thanks for the reply I only use shell v power I did test the cat with temp gun and its seems to still be working ok as about 100 deg hotter on the outlet side, then the inlet although I did remove the pre cat the other day and that was abit melted! The car has 90'000 so maybe time for a new cat,

Next question how much are they

Edited 27 April, 201511 yr by matt136

I use GSF, good quality items as original supply.

Check their web site they occasionally have 35% off at weekends.