Upstream o2 sensor for CLS 320 CDI. Thinking if I can get a deal on the sensor, may aswel change it for peace of mind. Mercedes refuse to give me the part number for some reason. I have seen an o2 sensor on EuroCarParts at approx £178, whereas the Mercedes part is £235. The EuroCarParts is a Bosch item, but shows for the E Class rather than the CLS. Would it be the same part for my car? If not, any recommendations of where I may be able to get one? EuroCarParts Part No.: 710221685 Help greatly appreciated. Edit: Also found the above part on another site for £126. So if someone can tell me if it is the right part, would be great! Or tell me how I can find out!