oil pressure gauge wide movement range (1 Viewer)

[landarcht]

It's been a few months that my LC's oil pressure gauge pointer would sometimes point to the lowest tick mark on the gauge, see attached photo, I was on highway today at a bit over 40mph, even when I was at 55, it was pointing to the lowest. What could be causing it? I remember before it always stays about mid point, and would go higher during acceleration. My car has also had the check engine light come up to indicate the P430 code right side Cat? faulty. But the light would go away after a few weeks, then come back up couple weeks...very weird pattern. I replaced two O2 sensors, but that kept the light off about a month then it started to go and off few weeks at time again. Is it related to the low pressure gauge?
My car is due for its regular service, so I will have it checked again. Though I have to say that the car drives the way it has always been, I have not noticed any difference in engine sound, performance, ride or any other noticeable behavior.
Very strange..

 

[jblatl]

You need a new sending unit.

 

[Jeepster09]

Most manufacturers don't use guages because of this erratic-ness. You most likely have a faulty sender.

 

[2001LC]

What year?

 

[landarcht]

2005. I forgot to add that I did replace w/ a new sender unit when the gauge was first discovered dead and won't move at all.
Another thing I noticed was that low fuel light comes up early than usual before. It lights up with needle slightly before the last tick...are these related? All gauges work fine.