89 200q oil pressure warning flashing on display

[Lino M. Valadas]

Gentlemen

I'm in the process of debugging an oil pressure warning light that won't
give up.  The pressure gauge shows good  pressure so I suspect the pressure
switches.  I have just replace the 1.8 bar, so that ought to be good.  The
0.3 bar though, is part of the pressure gauge sender and harder($) to
replace.  The test of this sender (WK) as per Mr. Payne's web page
instructions (Thank you Phil) shows low readings with the engine running
(500-600 ohms instead of infinite).  So I could very well need a new sender.
But what bothers, me and I'm hoping somebody can explain, is why does the
oil pressure warning display goes off when I test it with the engine off,
ignition on and pushing the test button?  The display starts going through
its cycle and then gets stuck flashing the oil can.  What does that mean?
The owners manual never mentions what to do if this happens during this
operation.
I suspect that there is more to this than just the pressure switch. Would a
bad relay cause this?  Any BTDT?

All comments appreciated.

TIA
Lino
89 200q
83 ur-q
93 S4