Emmissions Light

[IWC]

I all, my emmissions light came on about 2 weeks after I had my car serviced (Its a 53 plate 1.8 SRI) The exhaust was replaced about 8 months ago. The garage reset the alarm (H02S) it cleared but after a week it came back, cleared it again and it came back the next day!!! It seems to come on when I'm on the motorway. I presume its a lambda sensor but front or rear? and is it a faulty sensor or could it be linked to the service?

[IWC]

Can anyone at least tell me if this is the front or rear sensor?

[ChrisBilly]

There's bank 1 and bank 2 but i'm not sure which is which. I doubt the lambada/oxygen sensor is actualy broken, its just picking up the fault.

[IWC]

Bank 1 Sensor 2. If its not the lambda sensor how do I find out what the fault is?

PLEASE HELP!!