Citroen Xsara Picasso Engine Oil Problems

Have had a warning light + alarm for low engine oil only when taking sharp corners. The oil level is perfect on the dipstick so was assuming it was some kind of sensor fault? maybe water contamination from the recent heavy rain? Question is...

My key only operates the locks remotely and I carry a spare battery just in case. The spare key is manual only, it does'nt work either. A neighbour has the same car and the same problem. Any ideas if this is a simple fix or what?

Hi My car keep on flashing the warning. Stop oil pressure is low. I have checked the oil but it seems to be ok. What would the problem be.

Just want to know what it means and what to do