Where is the oil pressure switch on a vauxhall frontera sport 2.2 petrol?

if its a frontera 'a' , on the 2.2 engine (with code x22xe) its an integral part of the oil filter housing and sadly, only on this engine, its not a cheap fix as i found out to my expense ( as i own a fronty with this engine ! ) the whole asembly is around £130 and you have to buy the complete unit. if its a oil pressure problem your having, then try changing/cleaning the relief valve first