[711wildcat]

My 2011 335d is in for an analysis of the check engine light, etc. The shop foreman told me:
1) The SCR System will need to be removed and replaced
2) The Air Mass Sensor will need to be removed and replaced
3) Decarbon Intake Valves and Intake Manifold. Of course he could not tell if there is indeed carbon build-up (unlike the old 524tD); but is highly recommended.

A little background on the car: 75K miles and accident free. The majority of these miles are interstate highway. It has been a great car until recently. For the repairs, I've been quoted $5,300 - but I asked for some goodwill and National is chipping in 30%, effectively lowering the bill to $3,000 plus tax.

Looking at this forum and BMWCCA forum, it appears like I'm not alone. The SCR and air mass sensor issue seem to be widespread with the 335d.

I'd value opinions on selling or letting it go and chalk up the experience to "lesson learned". Cheers.

[335dlci]

Is there any documentation that there is carbon build up or they are just speculating?

[711wildcat]

Originally Posted by 335dlci

Is there any documentation that there is carbon build up or they are just speculating?

Just speculation. They indicate that to verify that the intake manifold would need to be removed; however, that given a vehicle with 75k miles, it is more than likely the CBU is present.

[larrysing]

Originally Posted by 711wildcat

Just speculation. They indicate that to verify that the intake manifold would need to be removed; however, that given a vehicle with 75k miles, it is more than likely the CBU is present.

That should be an easy fix on the CBU: If they find it, they clean it and charge you for it. If they open it up and none is present, then they don't have to clean it. You might take a labor hit for the cost of looking in there, unless they can scope it for you.

As far as "trade or fix" you would have to make an economic decision on that.

[BB_cuda]

Scoping can not happen with intake still on. I've tried. You for sure can't get past swirl flaps. The other port is smaller. I never could get too far without lense getting black stuff on it from scraping walls. Intake pull is best way. Several of us have done this ourselves. Unsure of your mechanic abilities.

[bimmerup-sonny]

Originally Posted by 711wildcat

Just speculation. They indicate that to verify that the intake manifold would need to be removed; however, that given a vehicle with 75k miles, it is more than likely the CBU is present.

I can almost guaranty that CBU is there, mine is cleaned at 71K miles
and it only shows little power loss and no MPG loss.

Here are some pictures, 2 are the before and 2 are the after the cleaning
Email me if you want to see more pictures, I was surprised that it was this much CBU

[711wildcat]

Originally Posted by larrysing

That should be an easy fix on the CBU: If they find it, they clean it and charge you for it. If they open it up and none is present, then they don't have to clean it. You might take a labor hit for the cost of looking in there, unless they can scope it for you.

As far as "trade or fix" you would have to make an economic decision on that.

Economic in that I don't want to be faced with similar repairs three years down the road. Otherwise, not an economic decision. I may replace the 335d with an Audi S4.

So, here is the crux of the feedback I am seeking - is this the sort of thing one can expect to see? Despite being a solid car in other aspects, are the 335d owners letting theirs go or are they just putting up with the nuisance of performing the decarbonization of valves, replacing the SCR Tank, etc. every few years? Thanks!

[Hoooper]

Good chance the MAF code and possibly the SCR codes are resulting from the CBU. I think the best course of action in these cases is always to get the CBU cleaned properly, then see where that leaves you.

Most people on here arent putting up with CBU, they are performing the necessary repairs to keep it from happening. As for your average owner, they are probably either getting a reasonable price on CBU cleaning or are selling it after the cleaning.

[711wildcat]

Thanks Sonny - I've seen similar pics and I am wondering if this is just the nature of the beast...I rarely saw carbon build up like this on the 524tDs, unless they were low mileage with little to no highway. I suspect direct injection through the sidewall of the piston is a chief cause, precluding the semi-cleansing action one would see when the injector was over the intake valve. Keep of sell? Did not expect this sort of situation with it just over 75k miles...

[711wildcat]

Originally Posted by Hoooper

Good chance the MAF code and possibly the SCR codes are resulting from the CBU. I think the best course of action in these cases is always to get the CBU cleaned properly, then see where that leaves you.

Most people on here arent putting up with CBU, they are performing the necessary repairs to keep it from happening. As for your average owner, they are probably either getting a reasonable price on CBU cleaning or are selling it after the cleaning.

They quoted me around $1,200 for CBU removal - which IMO is reasonable considering all the steps that are needed to perform the task.

[WreckerX5d]

My way of the SCR failure I had (leveling sensor, within tank) was to just to make my car illiterate (stolen from Persian Whisperjet). It was much cheaper to get the BDP downpipe and BPC tune than to pay the $2500 for the urea tank alone, not including labor. This essentially was a gain in multiple areas as well. I now can use cheaper oil (Rotella T6), no more DEF fills, fuel economy went up (that's debatable, lol), parts replacement in some areas are easier, no need to worry about the DPF failing (it will happen, every single diesel with these will come across that), and more power (no one denied more power).

[335dFan]

If I were in your shoes, I would get the CBU cleaning done, clear the codes and go from there. If the other stuff comes back, deal with it then. From my following of these cases, there seems to be some post-CBU cleaning gremlins that need sorting but then you're good to go. I expect to experience this in the near future, having 54k miles on the clock. I do have extended warranty covering me until 84 months or 100k miles. I bought it new 46 months ago. I plan to enjoy it at least through 100k miles. But then I have invested a lot in the suspension, am retired, and use it mainly for road trips. Good luck to you. I drove an S4 before buying the 335d.

[Thecastle]

Just an FYI, the dealership can perform an engine flow test diagnostic to definitively tell if the engine is in need of a CBU cleaning. Given your mileage its likely this is the problem.

Not sure an S4 is out of the woods in terms of CBU, audi DI engine suffer the same problem too.

[OmahaDZL]

Originally Posted by 711wildcat

They quoted me around $1,200 for CBU removal - which IMO is reasonable considering all the steps that are needed to perform the task.

EXTREMELY reasonable...my dealership told me 3300. Seems to be quite a bit of variance from dealer to dealer.


However.....long term...if you love the car like I do... keep reading on the forum about solutions....like coding things out...blocking plates, catch cans......the answers are out there

[rulonger]

Originally Posted by 711wildcat

They quoted me around $1,200 for CBU removal - which IMO is reasonable considering all the steps that are needed to perform the task.

That seems a very fair price. I paid right at a grand at an indy shop.

I came out of CPO and within a month had an SES. My car was at 73 K miles and at that point I was in the same place that you are now.

What did I do? I paid for the CBU cleaning, installed a dp and EGR block plates and treated my car to a stage 2 tune. I got better mpg, eliminated problems that could occur (no dpf, no regens, no urea spraying, no CBU causing EGR) and unleashed more power. That is what I did, but to each his own.

Best of luck with whatever you do decide to do.

[geost]

I don't know how it is in AZ but here in Cali we are pretty much screwed with all this because of our emissions laws (damn CA!). Honestly though if I were you I would opt for the CBU removal first before proceeding with anything else.

My car was running like crap and throwing codes at around 60k miles. At first I figure it could be the fuel injectors going bad. But I took it to an indy shop and had CBU removal done. Almost $800 later all codes went away and never came back (knock on wood).

So far it's been running great with no problems. Stuttering is gone and engine doesn't rev weird like before. I had thought about selling it too before I had CBU removal done but ended up keeping it after. The 335d is just too much fun to give up so easily....unless of course I'm having major problems that require a boat load of $$... I'm around 66k-67k miles now, still eating my rear tires for breakfast.

[bimmerup-sonny]

Originally Posted by geost

I don't know how it is in AZ but here in Cali we are pretty much screwed with all this because of our emissions laws (damn CA!). Honestly though if I were you I would opt for the CBU removal first before proceeding with anything else.

My car was running like crap and throwing codes at around 60k miles. At first I figure it could be the fuel injectors going bad. But I took it to an indy shop and had CBU removal done. Almost $800 later all codes went away and never came back (knock on wood).

So far it's been running great with no problems. Stuttering is gone and engine doesn't rev weird like before. I had thought about selling it too before I had CBU removal done but ended up keeping it after. The 335d is just too much fun to give up so easily....unless of course I'm having major problems that require a boat load of $$... I'm around 66k-67k miles now, still eating my rear tires for breakfast.

Mine did not throw any injector codes before the CBU clean, the only codes I had were MAF and NOX related. But 6K miles after the CBU clean (at 71Km miles), I got 3 injector codes, each points to a different injector #, and got engine stuttering at low RPMs. I blasted with a double dosage of Power Service Diesel Kleen and the stutter went away. I've read that these injector codes may have to do with the DDE (computer) SW, I cleared all the codes and so far so good, engine sounds and behave normal.

[Hoooper]

Originally Posted by geost

I don't know how it is in AZ but here in Cali we are pretty much screwed with all this because of our emissions laws (damn CA!). Honestly though if I were you I would opt for the CBU removal first before proceeding with anything else.

You can still do a physical block off in CA to significantly cut down on the impact of CBU. EGR block/delete is basically just as illegal in all 49 other states as it is in CA. Only difference is that you have to switch it back every 2 years if you live in a smog county/area.

[montr]

Originally Posted by Hoooper

You can still do a physical block off in CA to significantly cut down on the impact of CBU. EGR block/delete is basically just as illegal in all 49 other states as it is in CA. Only difference is that you have to switch it back every 2 years if you live in a smog county/area.

With the EGR block, do you still keep the EGR cooler?

[Hoooper]

Originally Posted by montr

With the EGR block, do you still keep the EGR cooler?

I have with mine but you dont have to

[BB_cuda]

If your in Cali, keep the cooler on to be incognito.

[711wildcat]

thanks for the feedback everyone. Seems like the consensus here is to keep the beast and perform the CBU first, then go from there. I'll decide by Thursday night, and it's not an easy decision...I tend to get attached to my cars. The 335i xdrive is also an option that I am considering...Cheers!