Oxygen Sensor - Corsa

[MissMarple]

Im unsure whether ive put this topic in the right place but here goes..
I own a Corsa C 1.4 sxi (dont know is its relevent) and my EML keeps coming on. Ive also had problems with my battery (keeps loosing charge).
My mechanic has plugged in and it keeps saying that it is the O2 sensor. I had a new one fitted not so long ago. But then the EML comes back on after a few trips out! (very frustrating!)
Last night i had it in the garage for 2 new tyres, to have a new battery fitted and for my mechanic to see if the machine still says O2 sensor - still causing the light to come on.
This time the fault showed as only one of the sensors; last time it said 2.

Some people have said to me that these sensors are a pain in the arse and to just ignore the light..?? Im just getting a little fed up with going in and out of the garage because of it. My car is running fine by the way incase it is relevent.
Has anyone had this problem or have any knowledge about the blasted sensors??

Thanks in advance!

[Jimmyarm]

Just relying on the codes won't get you very far.

The sensors need reading with an oscilloscope or decent scanner to check what they are transmitting.

Then you can decide whether it's a duff sensor, faulty cat or an air/fuel issue causing the fault code.