I replaced the oil pressure sender unit on my ‘89 G20 a year or two ago. Prior to that it was pegged on below zero. Since that time it’s been working normally, up to a few weeks ago. Now it’s frequently pegged to infinity, or way yonder passed the 60 reading on the gauge.

When I come to a stop it behaves normally, going down to about the 1/3 mark. For a while during this episode, it would work at all rpm ranges for an hour or so and then just start flying way up to peg on the max.

I’m wondering if it’s the dashboard gauge itself that has gone past its pull date.

 

The oil pressure sender may be bad again. Did you get an off brand when you replaced it? You can also put in a mechanical gauge to verify the readings.