Ok - there's a lot on the general internet about this issue on 272 and 273 engines, but wanted to share my real world first hand knowledge of it with my 2008 R350.

Anyway, the P0025 and P2006 are the OBDII codes for camshaft position and intake stuck open.

I've managed to solve P0025, which is typically caused by the Camshaft Magnets or solenoids. Part is typically about 30 bucks from the dealer. My comment here is you could by all 4 magnets, or you could take the time to diagnose what code itself means. In the case of P0025, or "B" Camshaft Position - Timing Over-Retarded (Bank 2), B is for the exhaust side and Bank 2 is for the cylinder bank opposite of cylinder 1. In our specific case, this is the driver side cylinder bank and the exhaust cam sensor is the sensor that is lower than the intake are you look at the two sensors in front of you.

Also, there's video out there, but the only way to remove the cam sensors on bank 2 are to pull the heat exchange cooler attached to the oil filter and the power steering resevoir. In both cases, you will get a spillage of p/s fluid and coolant. External torx 30 socket should do the trick!

I've reset the computer and so far, can start the engine everytime. The issue I was having was being unable to start the car. These codes say you'll have power loss and stalling, but it seems like you also can't start the car too.

The p2006 code seems to be related to the infamous tumble flap actuator which is made of plastic and typically breaks. You can barely see these actuators towards the top/front of the engine, but you'll know immediately if they fail if you can move them, which I can in my case. So, in researching replacement options you can;

1 - take it to dealer and have them replace everything and you probably won't have to deal with it again, but you'll spend 1000s and still have the crappy oem plastic bits.
2 - take it to indy shop, they'll have options to replace part on intake or recommend complete intake replacement, still $$
3 - DIY, replace the entire intake manifold - Ebay has them around 300-400 right now
4 - DIY, replace the plastic part, there's legit companies like Uro Parts and AllGermanAuto that sell their solutions for around $200
5- DIY, replace the plastic part from Ebay - not much to say here except you'll find the parts are made of aluminum and prices are 40-100
6 - DIY, Dorman - Rockauto - $40 - aluminum rocker with aluminum arms already attached.

I went with option 6 and bought the $5.00 left/right intake gaskets OEM at my local dealer. Hopefully, the removal/installation of the manifold goes as smoothly as I've seen on some of the youtube instructional vids.

So, my symptoms that prompted me to get at this repair was certainly a rough idle, but I also seemed to having starting/stalling issues. Was that typical for most of you with this problem?

 

Just updating this thread, but after some researching I think I may have a bad crankshaft position sensor. The symptom I have is that the car will crank, but not start. At first it seemed to do this after the car was driven and warm, but now it's gotten progressively worse and won't start when cold. However, I try to start it 3 or 4 times and then it starts, runs rough, then smooths out the idle. The common issues seems to revolve around

1 - bad relays
2 - dead battery
3 - crank position sensor
4 - fuel pump

did i miss anything?

 

Just to close the loop.

Finally completed all the repairs related to the Pierburg Intake Manifold. First, the actual repair of the Tumble Flap Actuator on the front of the manifold is easily resolved with an aluminum part from Dorman. Taking the manifold off is no easy task and when I pulled it off, there was a cable still connected to the throttle body actuator. Like many of the plastic connectors on this MB, this connector proved to be too difficult to remove, so I actually did the repair semi 'insitu' with the intake removed but resting above the block. Also, the various vaccuum hoses were quite brittle. A quick trip the local Oreilly's for about a foot of hose took care of the brittle hoses on the intake.

Lastly, the crankshaft position sensor is also not the easiest of jobs. And our bolt which holds the sensor is not a external torx bolt, but a standard torx bolt.

Sadly, after all this hardwork, when i went to fire up the car, I still had starting issues and to add insult to injury I then got the dreaded, 'drive to workshop, do not change gears'.

Ever resilient, I continued to troubleshoot and scan trouble codes, but strangely no codes even came up. However, I had always had it in my mind to change the battery and aux battery.

Sure enough, upon removing the main battery, I saw a ton of corrosion and the two posts appeared to have lifted and there were bulges around them. A test and visual inspection at Batteries Plus from the salesperson there confirmed the battery was shot and that it was likely causing the erratic starting behavior.

So, two new batteries installed, R350 consistently starts right up, no error codes, but I still can't drive it because of the transmission error which turned out to be the ISM module.

So though the repair bill for a module and programming will come out to $1100 - I guess I shouldn't complain too much since our benz has been relatively trouble free with zero trips to the dealership until now. I would have liked to do this particular repair, but considering the costs for Star plus the actual part, it just didn't make sense.

 

So, it sounds to me like the codes were likely caused by the failing battery...

How do you know you need a new ISM. Could that not also be a residual issue from the battery? I would ask that the dealer flash it first to just be sure...

Failing batteries on modern networked cars cause all kinds of chaos.

We just went through it with our 2006. At the worst point I pulled it into the garage running on 5 cyl and throwing all kinds of codes... glad I knew better... took it the next morning to my auto parts place and completed the swap right in the lot.. drove it to work again and all cleared up. She's been running fine since.

I bring it up since it is highly unusual for stuff like that to just cascade and fail....