oil pressure sender

[jw]

i have recently rebuilt my williams clio "n193 xvm" all is fine except for the oil pressure sender it seems to be working in reverse, i have taken the spade connector off sanded the connector and put a dab of grease on it, tried the same proceedure on the gearbox earthing points, so is it just a case of a new sender or is it definitely an earthing problem??..

any ideas would be great cheers..