'95 C280 Oxygen Sensor
 

I just picked up a Bosch # 13427 (0258003427009) Oxygen Sensor to
satisfy my check engine light. I checked the Bosch site and it appears
to be the right one.
I can't identify or locate the existing one based on the part I bought.
Can some one tell me where it is located and installs? Or is this the
wrong part?
thank you

Which O2 sensor? IS your problem with the front (main), or the rear (downstream) 02 sensor?

Did you have the codes read to find out which 02 sensor is faulty?

You need to have the codes read in order to know exactly which O2 is faulty, just as Dave mentioned. However, I could tell you which one you purchased just by the length of the wire. The main O2 has a very short wire about 20cm. The secondary O2 has a very long wire probably double in length or more.
You better hope that the main is faulty because the secondary is a pain in the *** to change.

Vinamg

A Check Engine light is an emmission system fault warning.
There are approx. 60 faults that will trip it.
There is a diagnostic module to retrieve the correct fault. Until you retrieve these codes, it's a crap shoot. Can be as simple as an unplugged sensor/vac hose.
At the price of parts, I would not change anything until you have read the diagnostic codes . That is why they are there.

The O2 sensors are in the exhaust, under the car. The mixture control one is in front of the cat and the cat testing sensor is at the rear.