Hey Robster,
Funnily enough just tackled this problem this weekend.
I got the oil level sensor error code too when it went in for a diagnostic at a BMW garage. Worried me as I apparently have a slight leak from the oil filter housing and sump gasket, and didn't want the oil to get low without me knowing and driving the car!
Was checking the engine oil level regularly due to this worry, fortunately the engine oil level didn't change.
Just did an oil service yesterday and used the opportunity to change the oil level sensor with an OEM replacement, Hella brand. Part No 12617508003.
Cleared the code and hopefully it won't come back!