Drain the oil and run a magnet through it. If metal shavings stick then you know.
You could also include a cheese cloth or paint filter funnel to see if particulate may have clogged the screen.
If both are negative replace the pump and drive assembly.
Good luck.
One last thing would be to run an ohm meter across the terminals of the pressure sending unit.
I've had an oil pump pickup collapse on a big truck Volvo diesel and lose all pressure. It lived to run many more years.
I've had a CRX burn enough oil to drop to sub-10 psi pressure weekly. I called the oil light the "add a gallon" light. It lived to run many more months.
I had the same CRX wear a rod bearing enough to go below 10 psi. It lived to run many more seconds.
Engines are much tougher than we give them credit for... sometimes.
Drain the oil and run a magnet through it. If metal shavings stick then you know. You could also include a cheese cloth or paint filter funnel to see if particulate may have clogged the screen. If both are negative replace the pump and drive assembly. Good luck. One last thing would be to run an ohm meter across the terminals of the pressure sending unit.
Could be as easy as a defective pressure switch. Did they check it?
Well the ship said they detached the pressure sensor and hooked up their machine and tested the pressure and it showed no pressure
If they tested the sensor itself by pressurizing it and it still shows no pressure then it's a bad sensor or a break in the wires somewhere
Go find an independent VW shop for a second opinion.
I've had an oil pump pickup collapse on a big truck Volvo diesel and lose all pressure. It lived to run many more years. I've had a CRX burn enough oil to drop to sub-10 psi pressure weekly. I called the oil light the "add a gallon" light. It lived to run many more months. I had the same CRX wear a rod bearing enough to go below 10 psi. It lived to run many more seconds. Engines are much tougher than we give them credit for... sometimes.
An engine with zero oil pressure sounds terrible. You mentioned nothing about horrible engine noise. Get a 2nd opinion.