Z4 2.5si Intermittent P0012 engine light and idle issues (Solved)

[TF747]

Hi guys.
I'm a recently new owner of a 2.5si with 48k on the clock.

I've had an engine light pop up and go away on it's own a couple of times in the last month. I had the code read and it returned a P0012. It was then deleted and didn't return for a few weeks. When the light is on the car feels to be down on power and the MPG rose to over 50mpg at 60 mph which is way better than it should be.
I'm also having issues with the idle when the engine is warm. It will occasionally drop as if about to stall and occasionally rise and hold itself at 2000 revs until I blip the throttle.
Any thoughts??
Thank you in advance for any help you guys can offer! If you want any other info i'll do my best to give it!

 

[ph001]

The P0012 code would usually relate to the VANOS solenoids - very easy fix, just watch this... https://www.youtube.com/watch?v=KhViQO71KLo

If that doesn't fix it it's more than likely to be the Eccentric shaft sensor or Valvetronic motor. I suspect the latter more likely in your case but the sensor certainly needs to be checked.

See here... https://z4-forum.com/forum/viewtopic.php?f=3&t=106038&p=1543335#p1543335

I'm 99% certain it will be one of the issues listed above.

 

[TF747]

Alright thanks a lot mate, I did think it was the solenoids myself. The garage I bought if from checked them and said that they were clean but I'm still a bit sceptical!
I'd be able to sort the solenoids myself for a couple hundred quid. Do you know how much the sensors cost and how big of a job it is to replace them?
Thanks again!

 

[ph001]

Solenoids are widely available for about £30 ech and a doddle to fit. The oem number is 11367585425, but aftermarket ones seem fine.

The eccentric shaft sensor is more expensive (circa £300) and I wouldn't fit anything but OEM. Fairly straight forward to change but of course the valve cover has to come off so you will need a gasket for that. As a first stab, you could just remove the connector and check for any oil contamination, clean it off with carb cleaner if so. The valvetronic motor can be removed with the valve cover in place... https://z4-forum.com/forum/viewtopic.php?f=2&t=105680&hilit=valvetronic+motor

I'd defo do the solenoids first and if that doesn't cure it, take it from there.

 

[TF747]

Thanks a lot, your help is much appreciated! Have a good day!

 

[Scooba_Steve]

If you got it from a garage give it to them to fix. Don't get the cheapo soleniods, they don't last very long.

 

[TF747]

I wish they would! They only gave a month warranty with it and i'm a couple of weeks past that unfortunately. Don't think they'll do anything at this point but it's worth a try! And thanks for the advice.

 

[ph001]

Just watching this video around the 8min mark would confirm that the valvetronic motor can indeed be replaced without removing the camshaft cover... https://www.youtube.com/watch?v=JNTrQGxtB6I

 

[ph001]

Don't get the cheapo soleniods, they don't last very long.

I read the opposite over on Bimmerworld! (in that quite a few people have replaced with non-oem and they have been fine)

 

[Scooba_Steve]

Seems a mixed bag re the solenoids, i swapped both for OE as i figured they would last another 10 years!

To the OP you have more rights than their warranty, PM me of you want details though there is plenty of info online, don't let them fob you off even if you can fix it yourself, why should you.

 

[TF747]

To the OP you have more rights than their warranty, PM me of you want details though there is plenty of info online, don't let them fob you off even if you can fix it yourself, why should you.

Thanks a lot that's hugely appreciated, i'll be sure to take it back to them ASAP and let you know what they say! should be able to get there in the next day or two.

 

[TF747]

for all those interested. current scenario is that the garage cleaned and swapped the solenoids. if the car throws a P0015 then we'll know that it's just a bad solenoid!

 

[TF747]

Right so. Don't know if anyone is still going to see this.
After the shop swapped the VANOS solenoids I was expecting the P0015 code. I still got a P0012.
Could both solenoids have been bad? or is it something else do we think?

Cheers.

 

[ph001]

Well I would just be fitting two new solenoids and get rid of any doubt. They are not exactly expensive, well not compared to the other items on the list.

You don't need the garage to do that for you, it's about as simple as it gets!

 

[TF747]

Hah. i've just taken the oil filter off to check it given that it could be an oil related issue. first off the cap was well and truly stuck!!!!
secondly the BMW oil filters are supposed to have a cage thing on the inside aren't they?? well mine did not..
Can anyone confirm this??? Correct me if i'm wrong!
And ph001 i'm planning on switching them anyway!

 

[ph001]

 

[TF747]

I've changed the filter cap for a complete one and the car seems to be running fine. Only time will tell! Also My exhaust note sounds deeper and louder, could it be to do with changes to the oil flow?

 

[TF747]

Update : Since replacing the oil filter housing cap my engine light has not come back. However the lack of power and general odd running is still there. Next job clean the solenoids and if that sorts it i'll buy some new ones!

So if anyone is having a P0012 code in an n52, definitely check the oil filter and housing cap for seals and to make sure that it's all there!!!

 

[TF747]

So after a solenoid clean and a fair amount more driving I can confirm that the problems seem to have ceased. I will be keeping an eye on the solenoids and the eccentric shaft sensor.

Solutions == Buy and fit the correct oil filter cap with the internal cage (Fixed the P0012 code)
Clean the VANOS solenoids (dealt with lack of power and odd idling)

The funny idle happens occasionally still but i'm fairly certain that if I bought a new solenoid the problem would go away.