2016 touareg, 3.6L FSI. Has oil pressure fault P164D reduced oil pressure switch fault. This is the second time it’s been back for this issue and has same concerns as last time. Measure oil pressure with a mechanical Guage and at idle every 10-15 seconds or so it will go from 30psi to 2psi oil pressure and back again last time we put an switch in it then an oil pump and new gaskets etc everything involved with oil pump. Fault went away for 10 or so months now its back. During cold starts the oil pressure light comes on and off as it pleases until it warms up then it goes away. Pressure readings were taken while warm, is there anything else in this system that could cause these issues? Trying to either confirm a defective oil pump/switch or confirm another issue so it doesn’t come back again