well it was plugged into vag com and it stated bank 1 sensor 1 . but you can actually get to all 4 under the bonnet of course you have to take the air boxes out ect and to get at the rear ones its a bit tight but if you take the intake manifold off you can get at them both fairly easy.. engine out would be 4 new cats as you cant take the manifold off without the engine out i guess. but lambdas easy peezy
P2251
P0135
thats the codes i had