My daughter and I changed the oil recently on her 09 MINI (justa) at 74k miles and noticed oil pooling onto the parts just below the filter housing and on down to the pan as well as onto the connector in the photo attached. At first I thought it was an oil pan gasket leak but have cleaned it all up and now believe who ever changed the oil last didn't torque the cap down on the filter (recently purchased). We noted no new pools of oil and the pan gasket appears to be dry. She's had a couple P013A codes thrown and they clear with no issues, but now I'm wondering if the 02 sensors are good but oil has somehow fouled the connection.
I disconnected the black connector below and noted that oil was on the outside, but none on the inside. Nevertheless, I sprayed the outside with the electro sensitive cleaner and wiped down. Cleared the code, restarted and no new codes thrown.
Opinions on whether I found the source of the P013A code?

looking down front of engine bay on drivers side, just to the right of the heat shield.