S70 2.5 10v Engine Management fault

I own a 1998 S70 2.5 10v from new with 50k, the car had been garaged for a few weeks and on starting the engine management light was on.

Code read carried out and informed by non-franchise dealer it was oxygen sensor; changed sensor and fault still exists, car now in a reliable/trusted garage and indictation is engine running lean, with the obvious checks for air leaks etc undertaken.
Mechanic as present checking all sensors etc. but any ideas gratefully appreciated.

[cootuk]

Are they sure it was the oxygen sensor code?
Is this the £150 titania sensor?

[Chris_Rogers]

I would suggest that you check the correct Bosch sensor has been fitted, not a universal one. These cars don't like anything other than the correct OEM sensor fitted.

Yes, noted. The first replacement was purchased from GSF but multi-connector was slightly different, therefore returned and correct one purchased from Volvo (£164 + vat)

Mechanic has now identified that engine is in fact running lean so investigation continues.

Thanks for response

Non-franchise garage originally stated code refered to oxygen sensor located in front of Cat. Hence replacement.

Now trusted garage/mechanic undertaking a code read out identifies same code, also has now identified that the engine is actually running lean, so investigating reason for lean burn.

Thanks for response