Odd Oil Pressure Gauge Behavior (1 Viewer)

[Somebodyelse5]

Hoping someone can shed some light on this odd gauge behavior. I noticed last night, that the oil pressure gauge on my '99 does not go to zero right away when the engine is off... with a warm engine, the oil pressure reads at ~1/4 without keys in the ignition:

When the motor is cold soaked (over night) the gauge is almost at zero:


When the motor is running (this seems normal, if not a little high):

Is this a sending unit issue? something else?

 

[2001LC]

Only a guess, gauge may be bad. I don't think it gets any power to display reading from sending unit with key off on stock rig (no wire messed with)

 

[nissanh]

It is a ground signal (negative) that is sent to the gauge in the dash. May be the sending unit on the engine has a short circuit and a minor current is sent to the gauge cluster. It's not that expensive, so replace it with an OEM and see what you get. the sending unit is easy to replace.
Once you remove the sending unit, open the casing (4 tabs holding the casing) and inspect inside. It may need some cleaning, and then you can put it back.

 

[Tahomatom]

I had to replace my gauge recently. I cant remember the specifics but it was cheaper part and a job. Takes 15 minutes or so. There is a write up on it somewhere.

 

[Somebodyelse5]

Awesome, thanks guys, I will get a new one ordered

 

[nissanh]

 

[2001LC]

To be clear oil sending unit is on oil filter/cooler housing. Oil gauge is what you see in Dash.

First google hit:
3 Common Oil Pressure Gauge Problems | DoItYourself.com

3. Oil Pressure Gauge Reading Too High
"Another common oil pressure gauge problem is a reading that’s too high when your engine is idle or when it's turned off. The gauge should never read very high when you’re not driving because the engine should be fairly cool due to inactivity. If you park or idle your car after driving and your pressure gauge reading does not return to a lower number, the gauge is defective.

There are many reasons why an oil pressure gauge may be broken. Replacing the gauge itself should be the first thing to try, but if your issues continue even after a new one has been installed, check for other problems. Make sure the wiring in your dash is not shorted or faulty, and consider taking your car to a mechanic to get your oil pressure sending unit checked or replaced. Or, if you’re an eager DIYer, you can even do it yourself."