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24 Posts
Discussion Starter #1
Hi all,

Hoping you guys could be my saviour here.
My ecu was submerged in water and provided a very stutter drive home 2 days ago

I dried it out, resealed properly and added silicone for an extra layer of protection

I am 100% sure the ecu is fine and this is a true mechanical error, not mechanic due to the symptoms that I shall list below. There could be a chance it is the oil pressure switch and for the small price of £7 I can easily pick this up tomorrow and install and go for another drive. While I'm there I may also pick up an oil pressure test gauge as I read this would be handy in future diagnosis, I hate return trips!

Symptoms :

Not a great starting idle, revs fluctuate for a few seconds, maybe 5 to 10 then it normalises.

This may be because I am using an oil thickener (wynns stop smoke) as I'm burning oil from what I believe are my valve stem seals this has pretty much fixed the oil burning and oil produces a small puff of smoke when the engine is hot and we've been idling for a good few minutes.

No error lights, engine management lights or codes are stored present on the vehicle, even at start and drive away.

I drive away and engine sounds rougher than usual but clears up to normal after a few moments of gentle driving.

I believe this is because of the oil pump has started taking a while to suck up the thicker oil.

After about 20 minutes of driving the engine is up to temperature and everything is nice and hot. As soon as I stop the car will produce the red oil pressure warning cc id 212 the car is also beeping.

Once I drive away this clears and the beeping stop.

A few minutes later the symbol reappears but no beeping.

Engine feels fine but I'm driving real gentle just in case this is a real oil pressure warning and I do not want do any damage.

Once I stop the car starts beeping, I drive away but the error is still there.

I recently changed sparks and oil filter and air filter and they were all in bad condition

I have recently purchased the car the last recorded service was 5 years ago. By the state of the parts I would agree.

Cars mileage is 112k

Engine is a n46.

Any advice would be great.


24 Posts
Discussion Starter #3 (Edited)
Thanks for the post, but I do not want to go down this route.

My car is 2005, so 16 years old. Theres a small chance it's the oil pressure sensor, which I will change tomorrow and take the car on another light and gentle test drive.

I'm aware that it takes around 20 minutes for the "pressure to drop off" , so Ill turn around at around the 10 minute mark.

I highly doubt that this will fix the issue.

Following this, I believe the next best plan action is dumping the oil and oil pan and visually inspecting the pan and pump for debris.

I haven't found any decent videos on this, can anyone share for my specific engine?

Do I have to remove the sub frame? Is it worth it?

Is it worth checked the oil filter too? I only just changed it last week.

Following this I'm out of ideas. I really don't want to total this engine, I can't afford it hahahah

Update: I found this :
My guides are still attached, I can see this at the top, however, I am still mentally preparing to dump oil and pan though.

Update 2: replaced the oil pressure switch, but noticed the oil return pipe on the crankcase valve was broken, sheered off completely.

Could this be the answer to our problems?

I have rung bmw and they have one for £40, I'm picking it up in the morning.

They're available for 25 on ebay but I don't really want to wait.

3/2007 328xi E91
3,217 Posts
... Symptoms :
No error lights, engine management lights or codes are stored present on the vehicle, even at start and drive away.
After about 20 minutes of driving the engine is up to temperature and everything is nice and hot. As soon as I stop the car will produce the red oil pressure warning cc id 212 the car is also beeping. [I presume you mean when you stop in traffic with engine at idle, as opposed to turning engine off?]
Once I drive away this clears and the beeping stop.
I recently changed sparks and oil filter and air filter and they were all in bad condition.
I have recently purchased the car the last recorded service was 5 years ago.
Engine is a n46.
As you have probably realized, the Oil Pressure Switch Warning Light could be due to:
1) Actual LOW Oil Pressure, OR
2) Defective Switch, Connector, or wiring.

Did you have an Oil Pressure Warning Light BEFORE you changed the Oil Filter?
Did you carefully examine the filter housing components, particularly the "Spool" on which the filter element is mounted, and install new small O-rings, 2 & 3 in the attached diagram?

ISTA ScreenPrints are attached for your 2005 E90 with N46:
1) Oil Filter Element Replacement REP Document, related to filter;
2) Oil Pressure Switch (B6231) wiring diagram SSP Document. That diagram shows the Pressure Switch providing a ground signal to Pin#10 of DME Connector X60005.

Of course Oil Pressure is always LESS when (a) the oil is HOT and less viscous, and (b) Engine RPM is low (at idle) and oil pump develops less pressure. It sounds like your warning light ONLY comes on when Engine & Oil are HOT, and RPM is LOW. That suggests an actual oil pressure fault rather than an electrical issue with the Sensor.

I'm NOT familiar with the N46 OFH and filter element, but many N52 owners in the US have found the "Quickie-Lube" places too often throw away the "spool" on which the filter element is mounted, or fail to properly replace the small O-ring on the lower end of the spool (TWO such O-rings apparently in YOUR case ;-).

So I would open the Oil Filter Housing, let the oil from the filter element drain back into the housing & crankcase, and then carefully inspect the filter element, spool on which it is mounted, and the small O-rings.
Please let us know what you find,

2005 E90 N46 Oil Pressure Switch SSP.jpg
2005 E90 N46 Oil Filter Replace REP.jpg

24 Posts
Discussion Starter #5
Hi George,

Thanks for your valuable input.

I replaced all 3 o rings myself and replaced them, but I shall check this out shortly.

I have changed the pressure switch just in case and in the process found that the return line on the ccv was sheered in 2.

This is a plastic line and after 16 years it was probably weathered and brittle.

The closest quickest replacement is bmw for 37GBP. This is available tomorrow morning.

For now, this has halted the rebuild, but atleast I have plenty of clearance now to get to the oil filter

5,495 Posts
Obviously you'll fix the broken tubes you've found; I've had vacuum leaks affect oil pressure enough to trigger VANOS codes, so anything is possible.

If not: I've never had a pressure sensor sending unit fail to the point of being inaccurate, only non-functional. Given your description, it's likely a mechanical issue. In the Ford Triton world, this is very common when the chain tensioner seals fail; the easy give-away for that is a chain rattle on cold start. That domino effect starves the cams and phasers of oil, leading to phaser knock. Do you have any of those sounds, especially at a hot idle? Fortunately, your chain tensioner is of a different design and easily replaceable, and is worth changing as part of the rebuild. If your engine has them, the easiest thing to check, clean or replace are the check screens upstream of the VANOS, but you'd likely be seeing all manner of VANOS codes as well.

Remove the oil pressure switch and install a mechanical gauge to check your actual oil pressure. I have no idea what the set-point is for your engine, but again from the Ford world, pressure needs to drop to under 10psi in order to trigger the light, and I don't doubt this is similar. When I pulled the chain cover on my 150k mile F150, I found the starboard chain guide missing completely, its tensioner belching oil, and its phaser able to spin a few degrees. After replacing the chains, guides, phasers, cam followers, lifters and tensioners, I pulled the pan to find what was left of the guide clogging the pump pick-up screen. Despite the oil pouring from the tensioner and mostly bypassing the starboard head, the oil pressure light never came on. Not directly applicable to you, but the engine basics are the same.


I'm not familiar with your specific engine, but being an N-series, it may be susceptible to the serpentine belt ingestion issue that can occur to the L-6s when the belt gets oil-soaked, slips off the pulley and ingested through the front crank seal. The resulting oil pump blockage would starve the engine of oil, but it would do it all the time, especially when cold, which doesn't fit your symptoms. From the sounds of it, it's a combination of oil getting less thick as it warms, and mechanical wear. Cam bearings/ledges? Rod bearings? Main bearings? Any of the above? How's the oil look, any glitter? Use a stethoscope to listen to the cam cover, timing "cover", and oil sump to try and isolate any bad noises. If possible, check crank end-play to gauge the condition of your thrust bearing. I'd still want to pull the pan for inspection, otherwise you'll never know for sure. If you find bits of guide, you've found the culprit.

24 Posts
Discussion Starter #7 (Edited)
Hi duked.

Thank you for sharing your experience with me, I found it insightful and revelant and it goes with my thought process.

I am picking up the ccv today from BMW as soon as it arrives.

As soon as I have finished installing the ccv and air intake I plan on raising the car and attempting to the drop the pan.

I expect to see parts of my timing chain in the pickup.

The car is long due an oil change (according to service history 5 years ago). Giving this, plus the engines mileage at 112k I had a big hunch that it is the chain.

As for the grinding or untoward noises there is none only upon start for a few moments, then it clears. And the noise heard is just rough sounding engine. No tapping or grinding, just doesn't sound happy for a few moments.

My engine has no dipstick so I can not tell you the quality of the oil until its drained.

And I only plan on dumping the oil once, so I'll be draining the oil, removing the sump pan and visually inspecting.

Unfortunately from my research, I'm not sure if the sub frame needs to be removed, and if it does I will need to purchase an engine support.

I also need to purchase an timing kit too by the video I'm watching.

I'm definitely not a mechanic but I'm smart enough to problem solve and fix obvious broken things. From what I've seen, this job isn't beyond my scope, it's just big.

If I do have to replace the chain and guide, do you guys know of any great tips / videos etc that'll make my life abit easier?

I'll obviously keep you guys posted with more new data.

Cheers guys

As for testing the actual oil pressure is there a tool I can buy from a store to do this, Halfords, eurocarparts ? My Googling led to nothing, only available to order on online.

Update: I found this regarding an audi A4 during my research.

I'd like to hear your thoughts.

The issue is, how did this pop break in the first place? The thick oil plus the stop smoke?

After I install the pcv, I am just going to do an engine flush, theres probably so much gunk in that sump and refill wi frsh oil.

My engine still needs to get the valve stem seals sorted, so I have to run a slightly thicker oil otherwise itd be puffing like mad.

The engine is also on 112k. I usually use 10w40

24 Posts
Discussion Starter #8
So, today I finished the rebuild and took it out for a drive

Lasted about 45 minutes than ccid 212 popped up.

During my preinvestigations yesterday I found that the guide rail for the timing chain as alot play. I fear that is has snapped half way down and the grubbins are blocking the pick up.

So either later or tomorrow, the rocker cover gasket is being removed and I will have a better visual inspection of the guide. Seeing as the car is in 112k and wasnt very looked after well by the looks of it, this is a very overdue job.

If the guide is broken, is there anyway to get the sump without dropping the frame and buying an engine support?

This is a very common problem from my research. I really don't want to drop the sub as this looks like alot of work.

Something to note, I am getting oil pressure even when hot, I know this because I am still burning oil at idle.

This is why I believe I have shit in my sump. I'm using 10w30 and stop smoke. So my oil is really thick right now.

If there was debris in my oil and sump, it would stay seated at the bottom of the pan until its hot and thin and then it'll be sucked up and blocked.

When the engine is switched off, it drops back to the pan until it is in the pickup.

There is always the chance of a worn engine, but I believe that this is more likely.

24 Posts
Discussion Starter #9
So to bump this thread.

Today the sump and pick up finally left the vehicle and it was full of plastic. Only a tiny part of the guide. The pick up mesh was blocked a and brittle, as a result it broke apart and blocked the pickup.

Now to put the bitch back together....
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