BMW n52 125i - Low oil pressure warning HELP

[Billygeorgedear]

Hello everyone !
I’ve currently got a 125i n52 130k miles


I’m looking for some advice regarding an ongoing low oil pressure warning issue. I want to clearly outline everything that has already been checked and replaced so far to avoid repeating steps.


Background


The car intermittently throws a low oil pressure warning. Over time, it will also begin to throw VANOS/solenoid-related fault codes, which the garage believes is due to oil starvation rather than an electrical fault.


Work Carried Out So Far
Oil pressure sensor
Initially fitted a cheap Chinese oil pressure sensor from Amazon (yes, I know this wasn’t ideal).
A new genuine BMW OEM oil pressure sensor is arriving today and will be fitted to rule this out properly.

VANOS solenoids
Both VANOS solenoids at the front of the engine have been removed.
Cleaned thoroughly.
Tested with 12V and confirmed to be operating correctly.

Oil check valves / non-return valves
Removed and inspected.
Very little debris found, but cleaned regardless.

Oil pressure control valve
Removed and replaced with a brand new unit.

Sump removal & oil pump inspection
Sump was dropped due to an oil leak from the gasket.
Oil pump inspected internally using a camera.
No visible damage, debris, or silicone found inside the pump itself.
Pump deemed to be in good condition.

Oil pickup
Pickup pipe removed and inspected.
Metal gauze cleaned.
Rubber seal checked and confirmed to be in good condition.

Reassembly & service items
New sump gasket fitted.
Fresh oil and new oil filter installed.
Plastic filter cage and O-ring are present, correct, and in good condition.
Additional Findings
Silicone was found in the bottom of the sump, though not inside the oil pump.
The garage believes the issue is mechanical rather than electrical, as the car eventually throws solenoid fault codes due to lack of oil supply to them.
Current Status

Next step is fitting the OEM BMW oil pressure sensor, but if that doesn’t resolve the issue, I’m looking for ideas on what else could be causing low oil pressure given everything above.


Any input or similar experiences would be much appreciated.


Thanks in advance.

[JustAnotherSportsCar]

If it were me, while I had the parts out of the engine, I would have just replaced them with new genuine BMW parts regardless of how they looked. These engines are getting pretty old.

Probably a stupid suggestion, but are you sure your oil level sensor is reading accurate? Low oil level in higher G corners and driving on steep inclines could be causing you brief moments of the sump sucking air. If it sucks enough air a few times, the air will be messing with your VANOS.

It’s a stretch but if your PCV valve failed, it may cause some oil related issues.