Low oil pressure at startup after oil change

[carlc376]

I have driven the car each of the the last few days (after resetting the filter) with pressure remaining proper based on the RPM. The Low pressure message and 0 on the gauge has shown up again. After a restart of the engine, the pressure is showing again, but is lower than expected.



I reset the filter again this morning and confirmed that there is no extras gasket in the housing. I started the car and see the expected pressure.



Is it possible that the plunger in the filter housing is slipping off the filter causing the pressure gauge to react in this manner? I noticed that this was in the housing, and it does move freely.



I have still yet to confirm on a mechanical gauge, but I would suspect that if the pressure was actually that low, the engine would be making some noise.


I am still considering replacing the sensor, and possibly the filter at this point.

[0stones0]

I would suggest the filter being replaced, as it is inexpensive and you take away the probability that the current filter is faulty.

[carlc376]

Alright, I replaced the pressure sensor and the filter. I started it a few times and the pressure appeared to be normal each time. I will watch it for a few days and see what happens.



Thanks again for all the help.

[carlc376]

Well, the filter and sensor worked for a few days...then the gauge went back to 0. Same as before, no noises, no codes, etc. So I will check the wiring to see if there are any breaks or other loose connections that might cause this. I inquired with the dealer and they suggested some old oil sludge might cause this. So I may also just deal with this for a little while and then change the oil again to see if I can clear out any sludge.

[carlc376]

I also had my wife watch the gauge while I moved the wiring harness and found that I could make the gauge come and go when moving the wiring harness. I am planning to replace the connector and a chunck of the wire to see if that fixes it since it too is easy enough to do.

[FasNuf]

Sounds like you found the problem

[Bigdumogre]

I would change the filter imo. It’s cheap enough to not worry about it.
If I went that route I would do an engine flush and do a full change again since the oil was so old as is. Get one of those flush bottles. Drive it around for 50-100 miles and do a full oil change.

[carlc376]

I changed the connector for the oil pressure sender connector along with adding a bit more wire and wire loom to keep the wires away from the block (original was sitting against the edge of a bracket). My wife took it to work after the repair yesterday, oil pressure was normal each way. I go to do some cleanup under the hood (nowhere near the oil pressure sender), then when I start it to move it I again see 0 oil pressure (it still runs fine).


So...as suggested above, the next logical step is to do another full oil change to hopefully remove any sludge. I know they have engine flush products, are any of them recommended? In my 30+ years of DIY oil changes on various vehicles I have never used one, but I have never had a car that developed any sludge. (Back in the 3000 miles/3 months oil change days, I never went longer than about 2 months between changes.)

[carlc376]

Update: I changed the oil again (no "flushing" product). Gauge still reads 0. Now, I dig deeper into the wiring since it did previously react when I was moving the wire harness (even though I just replaced the connector). This has been such an odd experience that all of a sudden after an oil change, some wiring issue has shown up. Coincidence...maybe, but still odd.



Through all of this there have been no unusual noises from the motor and there is oil going through the filter so there is oil pressure.

[carlc376]

Yesterday the oil pressure gauge worked off and on. I checked the wiring again, no movement of the gauge seen when moving the wire harness/connector. I checked the connection at the gauge cluster, and that made no difference.


I also checked each wire of the connector. I know there should be 5v, grd, and a signal wire. When I checked, I had one that was 5v and the other two showed ground.



Does anyone know if the signal wire will show ground if the car running with the connector unplugged? Is there someplace else I can/should check? I have some experience with electrical, but I have never had this problem before. Usually replacing the sensor fixes it, as seen in other posts of this nature.



I would like to say that I learned my lesson and shouldn't change the oil again since the oil change seemed to cause it (but that is irrational and unreasonable). Although this was not occurring before the initial oil change.

[cawengr]

What are the wire colors ? On my the Gray wire is 5V the tan wire is ground and the tan/white wire is signal

[carlc376]

The Gray was 5v. The other two show ground. I know there should be one ground. It is the signal wire that is also a ground (while not connected to the sensor) that I am wondering about. Should this show a ground in this scenario? The funny part is that it did work after the sensor and harness was changed and is not now. I will go back in an test each while the sensor is connected (and car running) to see what I am getting on the signal wire.

[cawengr]

The Tan/White goes into the computer, who knows what you get out of it and a ground sounds possible. I would follow the tan and assure the ground is solid.

[carlc376]

That is why this is so frustrating. I am baffled. It has oil pressure or I would have known it by now. I will likely end up taking it somewhere to get looked at since I am out of ideas (I hate to do that, but something is not right). (There was a post that this was responding to, but it was deleted.)