[nicked8]

TLDR: Trying to understand differences in VANOS (camshaft) adjuster units 11367522290 and 11367583208 as I try to resolve a 2A99 code.

I have a 2006 E90 330i with about 126k miles and have been chasing some VANOS codes. Initially I was getting 2A82, 2A98, 2A99 and similar codes that seemed to switch from intake to exhaust when I swapped VANOS solenoids. After cleaning the solenoids didn't help, I replaced them both with Pierburg units from FCP Euro. This seemed to resolve the issue and I drove for a few months without any new codes.

Then a few weeks ago I scanned the car and 2A99 had reappeared. At no point have these codes ever triggered a check engine light - I've always seen them when scanning the car on my own. I cleared the 2A99 and drove the car about 500 miles to see what would happen. I scanned the car again and this time 2A87 had appeared - the first time I've seen this code.

So at this point I'm thinking I'm dealing with the broken VANOS adjuster unit bolts that have been subject to recall or a potentially cam ledge bearing wear. I decide to pull the valve cover and order a new gasket, eccentric shaft sensor (I had oil in my connector), and a bunch of the updated VANOS bolts with the plan to replace the security torx ones that are known to back out and break.

Well I should have done some more research ahead of time because I pulled off the valve cover yesterday and my VANOS adjusters are different - they don't have the rearward security torx bolts. My unit has a black cover on the back side (camshaft side) and no bolts - instead it has bolts on the front side (facing away from the engine). I go onto realoem and realize that my units must be 11367522290 which was used 09/01/2004 — 05/20/2009 and was superseded by 11367583208 from 02/02/2009. My N52 is a 07/2005 build so clearly has the earlier unit.

My question is - are these early units susceptible to similar issues with the bolts? All the front facing bolts look fine to me - all are present and none seem backed out. If I eventually need to replace the units, I assume I would use the updated part number?

Separately, if these older style adjusters don’t have the same bolt problem – what else should I consider as the cause of my 2A99 code? Obviously hoping it’s not cam ledge bearing wear. I took off the front intake camshaft cap and fortunately there were no grooves worn into the cap. It has the expected light grey wear, but there’s zero lip when I run my finger over it. The inside of the engine is super clean and has clearly seen regular oil change intervals so hopefully that helps. Of course, my codes are exhaust side which I can’t examine unless I get a timing tool kit.

Curious to hear any insight on the different adjuster unit styles as well as any suggestions regarding the code.