Hello everyone from sunny old England. Long time reader after getting my 2007 R56 Cooper S last July as a project with a friend, it seems this is one of the truly great sources for info on the R56. Long story short but came fully in my ownership in July 2025. With the dreaded 2885 code appearing.

Background

Before coming into my ownership the car had the oil feed line replaced on the turbo, nothing else engine wise.

Upon my first drive of this vehicle a year after ownership, I noticed a rattle from the wastegate and what I could only describe as acting like a naturally aspirated engine, not a turbo car. Noticing the valve cover was leaking, we also had an oil/coolant leak on top of the exhaust flexi. I changed the valve cover, turbo, oil cooler housing gasket and oil filter housing gasket. All leaks fixed, but still no boost plus and also the dreaded 2885 low boost plausibility code.





Code 2885 Testing

1. Tested the pressure converter with ISTA, it clicked, swapped with a known good unit from a friend's car, still no change and no boost.
2. Tested vacuum lines with vacuum pump and smoke machine, lines and vacuum tank held vacuum and also no smoke leaks thought this was good. Will come back to this later. However still currently drove awful
3. Randomly had a code about unmetered air between pressure sensor and throttle valve, replacing said pipe with noise generator with a silicone hose. At this point the throttle response in sport mode had changed and I noticed a slight bit more punch to the acceleration, normal mode still felt sluggish.
4. Had a random error code for the pressure sensor being implausible, replaced sensor. Has not come back up since.
5. Tested vacuum pump with engine on and came back with 23-26 (hpa is it?) on my vacuum tester which i read on this forum is within spec. Vacuum pump okay.
6. I had the idea that the vacuum pipes are old and cracked and when heated up could lose vacuum, so created a pipe that went from pressure converter to wastegate actuator. Acceleration improved once again.
7. Ordered vacuum pipes from BMW, installed and once installed noticed a very big difference in the throttle response and acceleration, yet when car warmed up going past 4k brings up 2885
8. Replaced hot side turbo to intercooler pipe. Once again noticed a few cracks from age, the car is feeling better after with the new silicone pipe, still getting 2885 when engine warmed up at 108 degrees celsius.
9. Currently awaiting a pierburg diverter valve, intercooler and also a silicone pipe from intercooler lower cold side to the plastic pipe that houses the pressure sensor. Will report on if this changes anything.

Final theory - Valve stem seals causing low boost

When the car gets to operating temp of 108 degrees celsius the exhaust smokes, when the exhaust manifold was off i did notice oil on the side of the engine near cylinder 3 & 4 exhaust ports, I'm going to presume the closet to the turbo so valve stem seals are shot. Could this oil leaking into the turbo then going into the cat cause low boost plausibility or not?

This is my story so far, any help or experience from you all, or even support would be grateful and if you got to the end well done.

 

Just in case you haven't checked code 2885 on BMW Fault Code Lookup...

 

In reply to those points, most covered in my post.

1) Vacuum system been replaced and checked multiple times
2) Leaks pressurised, Only two things to replace cold side lower rubber connecting to intercooler and also the intercooler, its 19 years old at the end of this year and a post on here said they eventually found a pin sized hole in the intercooler that caused 2885. So replacing intercooler as preventative maintenance.
3) Been tested in ISTA D test routine for this code error, it passed. Also used a known working one.
4) vacuum pump working and generating vacuum.
5) waiting on delivery of dump valve to test against the one that came with turbo.
6) operaiton of wastegate is a hella lot smoother than the old turbo and appears to be working perfectly
7) replaced turbo due to original turbo having a rattling wastegate.
8) DME? I hope not.

 

 

Pierburg Diverter Valve installed, different feel to acceleration but still can push the car till the temp goes up and boom low boost pressure 2885 again.

we wait now on the intercooler and cold side lower silicone hose and see where to go from there.

 

Todays job, while waiting for the intercooler to arrive was to finish off the valve stem seals to hopefully stop the smokey exhaust, fiddly job and my first time attempting this and timing an engine. Thankfully proved succesful. However, timing chain will have to be replaced as upon inspection its on its last legs and will be getting done in the next few weeks. However i'm disapointed with the state of the cams and cam caps. It its obvious that this car has had a hard life and previous owners have not kept on top of maintanence.

Code 2885 Update.

Replaced the lower cold side intercooler rubber pipe which was starting to rot out and at the top of the rubber pipe that connects to the plastic charge pipe was a mixture of oil, dirt and various other gunk.Test driving after valve stem seals replaced and the hose also being replaced, boost does seem to have slightly improved, code 2885 took longer to come back but we are still having issues at about 4000rpm at engine operating temperature. Lets see what this intercooler does.

I'm also wondering what condition my cat is in. I remember when my friend got the vehicle i inspected the cat and i thought it didn't look that great. going to remove the upper o2 sensor tomorrow and take some pictures of inside the cat and post them on here for some opinions.

 

Did you ever figure it out? I'm having same issue..
https://www.northamericanmotoring.co...-no-boost.html