Oil Leak at sensor
 

I have a 2000 9-3 that has an oil leak. I finally found that it is coming from a sensor on the side of the block, behind and on top of the starter.
This only leaks oil when the engine is running and I can't figure out which sensor this is.
The oil pressure sensor and oil temp sensor's are located closer to the oil filter according to the diagram that I have.
If anyone knows which sensor this is I would appreciate your help, so I can figure out which sensor to order.
Thanks in advance.
Bryan