Exhaust Sensor (Error 1137)

Hi all,

On a recent trip back home (Edinburgh to Durham) the dpf light came, which was suprising seen as though I was halfway through a 125mile trip!! Anyway kept it at 2000rpm and light went out after a few minutes. Anyway day later Exhaust warning light came (or engine warning light whatever you want to call it!!), car felt fine but i noticed that it was going through a purge cycle (was sitting at 1000rpm). Anyway engine warning light is coming on and off intermittently and I am getting a 1137 error code which I managed to narrow down to exhaust sensor I believe, which makes sense as I would be very suprised if dpf is blocked seen as though I drive to edinburgh and back every week from durham!!

My question is where is this sensor located? Ive got a new one and I hope this sorts it out, but does anyone know of a guide or can you point mein the direction of where its located? Any pictures etc? Would appreciated any help as Ive gotta head back up to work in edinburgh on monday morning and really would like to get this sorted incase the dreaded limp mode kicks in on way up there,

Thanks a lot in advance