Hi guys

I drive a 1990 VW Caddy 1.8 (HV) that came with the OEM set of VDO gauges (Oil pressure, Oil Temp, Volt meter)

When I turn the ignition on, The oil pressure gauge moves up to 1 Bar, but where it use to fluctuate whilst idling and driving, it now stays stagnant between 1 - 2 bar.

I have tested the oil pressure and thus I removed the likelihood of a bad oil pump.

The oil pressure sender unit (single pole) is located on the side of the cylinder head with a copper T-piece with another oil pressure switch. (I used plumbing tape on the threads between the head and the T-Piece to stop oil from leaking down. Any chance this could be an earth problem, hence why its not reading correctly?)

There are two other switches on the oil filter housing.

Please help me fix this as it is annoying the sh*t out of me. Any assistance with problem shooting would be highly appreciated.

So there are three switches plus the gauge sender. There should be a total of two switches and the gauge sender. Yes the tape could have insulated it and killed the ground signal. Easy to test. Hold it's wire tomthe block and should go to full reading.
If it does not jump the gauge is stuffed.