[timk123]

Hello all,

I recently got oil pressure low warning. and it goes on and off

All I could think about is faulty reading from the sensor but I actually recently replaced the sensor (3rd party).

So I checked few pressure readings

engine off :

2x inhg which is around 8~13 psi, I dont remember single digit

and when it starts it goes up to 78~85 inhg (36~41 psi)

I'm not sure if these reading are correct or not

what are expected readings when off and cold start?

[thejeremyman9]

What did it read when it gave the low warning? How is your oil level? How were you driving when it gave the low warning?

[LA1Z24]

With the engine off, there should be 0psi/inhg.

The N55 has a 2 stage oil pump. At low RPM you should expect around 40psi. At higher RPM you should expect more than 65psi. There is an oil volume control valve that may be bad.

https://www.fcpeuro.com/products/bmw...ve-11417622768

[timk123]

Originally Posted by thejeremyman9

What did it read when it gave the low warning? How is your oil level? How were you driving when it gave the low warning?

Haven't measured when warning come out. Oil level is at max (measuring from monitor) I was just cruising

[timk123]

Originally Posted by LA1Z24

With the engine off, there should be 0psi/inhg.

The N55 has a 2 stage oil pump. At low RPM you should expect around 40psi. At higher RPM you should expect more than 65psi. There is an oil volume control valve that may be bad.

https://www.fcpeuro.com/products/bmw...ve-11417622768

I guess I'll have to see sensor first then if it is bad i'll look into control valve
thanks

[harkes]

Idle should be +/- 40psi

[timk123]

Originally Posted by LA1Z24

With the engine off, there should be 0psi/inhg.

The N55 has a 2 stage oil pump. At low RPM you should expect around 40psi. At higher RPM you should expect more than 65psi. There is an oil volume control valve that may be bad.

https://www.fcpeuro.com/products/bmw...ve-11417622768

So I tested without oil pressure sensor (basically just unplugged it) and it still showed 19 inhg. what could this be?

[LA1Z24]

Originally Posted by timk123

So I tested without oil pressure sensor (basically just unplugged it) and it still showed 19 inhg. what could this be?

Is the sensor 2 or 3 wires? If 3, I'd suspect some type of short between either the positive or ground, AND the signal wire.

If it's 2 wires, there may be a short between the 2 wires. Looking into the connector for the pressure sensor, the wiring harness side...Is there oil residue? Sometimes when the sensor fails, it will send pressurized oil into the wire which CAN send pressurized oil all the way to the DME, and sometimes fry it.

A short could be a bridged connection with a pieces of wire, or a short could also be metal infused oil acting as a conductor that connects both wires.

This is primarily a mercedes thing but it can happen to any car. Last week I had a Mercedes in the shop for a crankcase breather. The solenoid failed and sent oil up the harness all the way to the ECM. Unplug the ECM connector and the ECM was full of engine oil

[timk123]

Originally Posted by LA1Z24

Is the sensor 2 or 3 wires? If 3, I'd suspect some type of short between either the positive or ground, AND the signal wire.

If it's 2 wires, there may be a short between the 2 wires. Looking into the connector for the pressure sensor, the wiring harness side...Is there oil residue? Sometimes when the sensor fails, it will send pressurized oil into the wire which CAN send pressurized oil all the way to the DME, and sometimes fry it.

A short could be a bridged connection with a pieces of wire, or a short could also be metal infused oil acting as a conductor that connects both wires.

This is primarily a mercedes thing but it can happen to any car. Last week I had a Mercedes in the shop for a crankcase breather. The solenoid failed and sent oil up the harness all the way to the ECM. Unplug the ECM connector and the ECM was full of engine oil

It is 3 wires.
I've replaced the sensor, and so far no warning.
might of been bad sensor..