False "Low Oil Pressure" readings.

[sailormike]

This is driving me crazy! It starts after I have driven the car for about 20 mins. and approach a traffic signal having to come to a stop. While driving the oil pressure is reading in the 30lb range. As I slow down the pressure all of a sudden drops to a zero reading from around the 12lb. range, which triggers the warning alarm. As I slow I have to put the car in neutral from the drive position.That causes the oil pressure to go to around a 7lb reading and stops the alarm. This will go on for the rest of my trip. Only to repeat every time I drive the car. We have replaced the "Oil Pressure Sensor" and had an oil pressure test performed showing, in spite of the oil pressure readings with the instruments on the dash, the oil pressure is fine The only other thing we have a problem with is the RPM gauge, that needle is jumping all over the place. My car is a 1999 with the 4.0 motor and about 145,000 miles.

ANYBODY have any ideas as to how to fix this?

[paulaurora]

Oil Pressure Sensor is defective or not fully screwed in or bad connector. Temp fix unplug the sensor and it will not give you anymore warnings. But i deff would try to replace connector and make sure its AC delco part not other brands i had a lot of issues with my 4.0 with other brands.

[elk]

I have exactly the same problem. I will try the neutral maneuver, for me stopping the engine was the way to go… I even took my aurora for a trip to the mechanics on a trailer for the first time in years

I had also the problem with the RPM gauge and it was because the bolt on the alternator screw was not fully screwed and a grounding wire which was in between was loosely jumping around while driving. I screwed the bolt up and problem was gone…

Looks like loose connector could be the reason here, I’ll instruct my mechanic to look at it closely.

[jimrockford007]

if you have to add oil between changed, drop in a quart of 15w40 next time you need to add it, I filled up with 5w20 after I reinstalled my engine and it did the same thing for a bit until I added a half a quart of 15w40 and now I have 20 psi hot at idle. Next time I change it I will run 5w30 and see what I get then. these engines are really sensitive to the viscosity of oil. my main bearings looked brand new when I had the engine apart for the case half reseal. solved my leaks only to discover the oil level sender is leaking now,..lol Ill have o wait till I change the oil to reseal that bastard.