Red is lost of oil pressure it's the worse you can get, you should pull over n shut the engine off... I would swap out the oil pressure sensor usually the main cuz of that, if it come on again after replacing it you got bigger but big issues.. my 325i would do it only at idle at a red light or stop sign.. n that's what people recommend in forms

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You are correct. Oil level sensor triggers the YELLOW oil light if oil level is low or if it has failed. The RED light is much more serious. It means oil pressure is low. Based on your symptoms of flickering oil light at idle only after a long drive it's not likely that the pressure switch is the problem. I have had quite a few cars of various makes and models roll into my shop with the same problem. Oil pressure switch almost never fixed it. I still recommend trying a new one though because you may be lucky. Other than that your engine is loosing oil pressure somewhere and much bigger repairs are in your future. What oil and filter are you using ?

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I use man filter n ams oil filter n I use redline 0-40 or Mobil1 0-40 I didn't replace the sensor it kinda went away on it's own I did do oil change n the change again a month later

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I had similar issue on my m54 (2.2L) with Castrol 5W-30 oil before. After I switched to Castrol 5W-40, the issue went away. It was probably not caused by the thinner oil but I suspected it was a combination of low idling (~ 500-600 rpm) and thinner oil which triggers the light. After I had fixed the low idling issue by stopping the vacuum leak and Vanos seals etc. the red flickering oil light has never come back.

I have read somewhere that the oil pressure at idle on our engines is a bit marginal. If we have low idle (anything < 700 rpm) then the oil pressure could get lower than the minimum required and triggers the low oil pressure light. I now have 5W-30 oil (LiquiMoly) back in the engine and it has no more red light.

 

I do have an idling issue with my car. Since I've owned the car it has idled pretty rough when the engine warms up. I've been trying to fix the issue for a long time but haven't figured it out (cleaned icv, replaced intake boots)

Never before though did the oil light flicker along with my idling problem until now.

Maybe this will call for an early oil change with different oil. My previous oil change was the first time I used oil from Walmart and didn't buy at stealer.


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OP, who replaced the oil pump? Was it a reputable shop that specializes in BMWs? Why was the pump replaced? Did the shop use the proper steps to ensure that the pump nut doesn't come loose?

 

The pump was replaced by a very reputable shop who I believe would have done a good job on it. It was within the last 20k miles but it was 4 years ago. Car hasn't been driven much up until the last year


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Oil pumps usually don't go bad, how many miles are on the car?

 

107k


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Oil pressure is created in the main bearings, the pump just supplies flow.

 

I think this is the sensor that plugs into the Oil Housing if i'm not mistaken--has a rectangle plug. If that's the code you're getting and the light is red, you're looking at the oil pressure sensor. Don't see how that can go bad. Maybe a hamster chewed on the wiring.

The yellow light is just the level.

 

Oil Pressure is a function of two things, engine speed and oil temp.

Oil pressure should hold at about 10 psi per 1,000 RPM. This pts the pressure at about 7 psi at idle. Oil that is hot is oil that is thin, and thin oil does not produce the pressure that the engine might be looking for. Hot oil at idle could produce insufficient pressure to make a flaky oil pressure sensor happy.

Your strategy from here should be to connect a mechanical oil pressure gauge to see what the actual pressure is. An alternate strategy might be to drain the oil and bump the viscosity a notch from 5w30 to 10w40, or something along those lines. If heavier oil cures the problem, then you are looking at a sensor or perhaps the oil pump is an El Cheapo Brand out of China, and this is catching up to you. I think what you really need to know is the actual oil pressure. I believe there are some unused holes on the side of the oil filter housing that you can use to port the oil out to a mechanical gauge. I have not looked at the oil filter housing for a long time, and I might be wrong, but I think you can plug in a mechanical gauge pretty inexpensively.

To be sure, low oil pressure at idle is unnerving, but is a condition that can last for a very long time without progression. I didn't see what you do to make the light go out, but if you increase the engine speed from idle to something below 1000 rpm, then I'm going to suggest that you just have a confluence of several weak links gaining up on you. As long as you can make the light go out by increasing the engine speed, you really don't have a lot to be worried about.

As with anything oil related, you want to be sure you are not out of oil. There is another light for that, but a physical check of the dip stick is certainly high on your list of things to be doing. Pull it and wipe it, put it back in then pull it a second time to see where the level is. If oil level is your problem, then the dip stick should be dry on the second pull and if true then you need at least two quarts of oil, maybe three.

 

I'm going to replace the oil pressure sensor this week and then try to measure the actual oil pressure to see if that's the problem. I think the root of the issue may also have to do with my idling problem.


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What is your idle speed (in gear if auto) and does it idle smoothly?

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It is manual and the engine speed at idle is about 600rpm when it is warmed up

And no, it does not idle very smoothly


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WHAT IS THE IDLE SPEED?

If the engine is approaching a stall, then the oil light is not a big deal. You are obsessing the wrong thing. You should be wondering why the engine speed falls, that's what is making the oil light come on.

 

Idle speed is about 600 rpm when warm, it idled pretty rough and it has done so for as long as I've had the car. The oil light flicker is new though. It would never come on before even with the rough idle. That being said, the oil flicker has not been present for the past 2 days and I have driven a fair amount


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RED LIGHT oil pressure.....tow to indy, or dealership...

 

Red is pressure, this is true. Tow to the shop and take out a second trust deed on your house to cover repairs is false.

Oil pressure can be low at idle for years and never be any worse. Turns out the OP has a low idle speed that allows the oil pressure to fall below the specifications that allow the sending unit to detect a fault that does not exist. Red light at speed is a serious condition, the red light at a stop sign is not a big deal, especially when the engine speed falls below 600 and the engine approaches stall speed. The low speed of the engine is the problem here.

 

If you bring the idle up with the throttle by 25-50 RPM and the oil light stays out, probably not a major worry.

I would consider replacing the oil pressure switch, I recall it triggers at like 5 PSI or something very low. If the spring in the switch ages with heat it can get weak and cause the light to come on prematurely.

Other things to consider is replacing the 2 small O-rings on the oil fill cap.

Also sort out the idle stability problem. Check Fuel Trims at idle, read about bad power brake boosters - http://forum.e46fanatics.com/showthread.php?t=1018617

 

I just wanted to point help here...5 lbs and lower with American sends a red light for sure...You explain it well better than I!

 

I've seen a couple m52/54 oil pressure switches that were leaking through to the connector and allowing oil to back feed up the harness. Symptoms were an intermittent red oil light.


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You know, SYNTHETIC oils..leak more, a lot more, than the old dyno oils?

 

They say ,,Oil Injectors'' those have one way valve and are cooling down pistons.
I have this problem after engine rebuild.
Cleen engine + mobil super 3000 5w-40 combination.
The deal is light does not come on in normal driving situations but when its 88-90 degrees ( thermostat mod ) and when oil temp is 95. If i drive uphill too long , stop, and switch to R position, thrn rpms go down all the way to 400 and goes up again. red light comes on and goes off.