CDi Oil Sender Switch

[daveandfleur]

My Vito CDi has long had a faulty oil light which comes on at odd times, stays on a while and goes off. It's done this for years. It can happen at any revs so clearly is not an oil pressure fault or the engine would have died long ago. The light also doesn't come on with ignition as it should. I can't find any reference to sender units anywhere but presumably there must be one. Any idea where? I've lived with the fault for years but am selling the van soon and don't want this putting buyers off,

Thanks
Dave