[octalon7]

Drives me nuts that this is such a crapshoot on replacing parts and crossing fingers. My state has emissions checks, so can't really ignore.

My car is heading in for the second trip (out of warranty) to tackle the next possibility.

First time they replaced the SCR valve, got about 1k miles before the SES light came back on.

Curious to hear of others experiences and which part ultimately did the trick for them.

[Yozh]

Floydarogers had some interesting experiences. May be he will post and link to his thread, I can not find it.

[koden]

When I registered my car here in Portland there was no inspection or DEQ. I got it from the dealer and the plates were mailed to me. I was under the impression that we were safe to delete anything we wanted.

I am fighting the same thing with 54K. Just got my K+DCAN cable today. Trying to wade through all the info on getting it to work on my laptop. So much info to sift through.

How many miles on yours?

[octalon7]

Just over 80k on mine. The emissions parts are warrantied until 70k, so you might want to try the dealer.

[m3driver999]

Hello,

Was in the same boat, finally fixed (some details in other posts I made in Forum)

Can't pinpoint which finally fixed my $4D16, but I did the following,

Esentially all done at similar/same time.

DDE update (done by dealer - indirect byproduct of FRM module replaced)
SCR injector new
New SCR fluid, Drain old passive and active tank SCR fluid
Used front Nox sensor (I was getting NOx codes at times)

I could not reset the NOx learned value, but I think the NOx sensor that includes module, may have had a more reasonable learned value which then combined with the new SCR injector finally got the code to go silent.

Seems the SCR + Nox is a closed feeback loop. SCR injected is linked to NOx reading; that is if the SCR fluid effectiveness is poor, then it may max out the NOx output of the engine, then it can throw SCR cat codes or SCR injector code, and/or NOx sensor codes -

Did all above DYI, as out of warranty, and dealer fees are $$.

There are other threads that have more background,

YMMV,

Good luck,

[octalon7]

Thanks. Was the code present for a period of time for you or did it just hit for an instance and then go back to normal operation? Mine just throws the code once, then is fine. If I get it cleared, it will throw it again in maybe another 400 miles, repeat.

[m3driver999]

Hello,

I drove with MIL ON for several months, as there would be a code set every few trips; then there was a urea tank code which set every trip; so I stopped clearing codes until I fixed the tank issue + fluid first,

But the 4D16 would appear every so often, and at other times the 4BB2 = "DeNox Cat, plausibility = Exhaust gas reduction not achieved within a plausible period."

Then did the injector and NOx sensor at same time and the codes did not return.

So hard to tell exactly the frequency of the 4D16.

Seems also there has to be a proper level of engine out Nox combined with a correct dose of urea for the SCR cat to be properly loaded and also the rear Nox reading well; then the rear Nox also feedbacks to the control of the engine out Nox. This is from what I've gathered reading forum and other documents found here.

Regards,

[octalon7]

Thank you for the info!

After the shop replaced SCR valve the code came back after about a 1000 miles. This time it came along with a NOX code as well. But just one occurrence.

I suppose next step might be the front NOX.

Unfortunately I'm not doing much of my own wrenching these days, so this could get expensive at the shop every time.

[m3driver999]

For $ reasons, don't visit the dealer too much, and have access to shop to do some light duty work, so had to jump into the 'deep end' of emissions equipment which is the 335d..

Some info I had found,

AdvancedDiesel with BluePerformance .pdf

It is on F15.bimmerpost.com

Technical document on the SCR system,

The NOx sensors do age with time, but I've seen posts where the issue is chased with new sensors and still it re-appears, not certain if there dealer process to load the cat with NO2, NO; and also clearing the front Nox learned bias/offset.

I think it is a combined fix of software + hardware, even as my car is late build 2011, it had a B-pillar sticker of service action 615 - which is incorrect;

There are documents showing there was a SA626 issued - but dealer said car was up-to-date; However, when FRM module died, and it was covered by BMW extended part warranty - then several modules on car were required to be updated to match latest firmware of new FRM - including DDE engine.

I think without the DDE update I may have been chasing issue longer.

Regards,

[Greck]

The code comes back after every second dpf regeneration cycle. If collected data between moment that you cleared the code and moment of the second regeneration of the dpf is bad(scr not efficient enough) it will show this code... basically to be at least somehow sure that you fixed the issue you have check the emissions monitors and if all of them pass - issue is gone. But in my case it was gone for 1 month and came back again

[floydarogers]

Originally Posted by m3driver999

...

The NOx sensors do age with time, but I've seen posts where the issue is chased with new sensors and still it re-appears, not certain if there dealer process to load the cat with NO2, NO; and also clearing the front Nox learned bias/offset.

Maybe I should author a post about this whole 4d16 issue - it's actually several separate issues that each result in a CEL with that as the final code. There have many posts here, and on the bimmerfest diesel forum, that cover this issue, but in a piecemeal fashion.

The fact that there are at least 5 separate components that can fail and result in a 4d16 complicates the diagnosis of the root cause, and solution.

1) The SCR Metering Valve (some people call it an injector; it sits at the bottom of the DPF) gets clogged or fails.
2) Bad DEF fluid.
2b) At some point, the DEF Mixer is also checked. This is an insert just upstream from the SCR Catalyst that adds turbulence/mixing to the DEF and exhaust stream. It can get corroded; about the only cheap part in the system.
3) One of the NOx sensors fails or runs out of lifetime. Exhaust gas sensors (O2 and NOx) have a finite lifetime - the NOx sensors will last only 80K-120K as far as I have seen. They're quite expensive - $400-$500 each.
4) Thermostat is also checked. Low operating temps can affect the SCR Catalyst (and also DPF regens.)
5) SCR Catalyst. Costs $1460 (price from realoem.com). Haven't seen that they fail very early.
6) DEF Container (SCR tank). There are so many reasons for this to fail - the temperature sensor, transfer pump, injector pump, heating element, etc. And BMW won't sell individual components or rebuilt tanks.

The above is pretty much the order in which BMW techs follow the fault tree to diagnose problems. Which means that the NOx sensors might be good (or at least marginal) and get replaced even though it's the SCR Catalyst or the DEF tank. At least some components in the DEF Container report faults, which can then be tracked down outside the above fault tree.

So, my 335d at 117K miles just had it's DEF container replaced - cost was $3200 at an independent (BMW Bellevue was $500 more expensive - all due to labor rates.) The active tank level sensor failed. I kept the tank and intend to rebuild it myself. The level sensor is a component that is available from VW - there's been a couple threads about that). There is also an easy fix for the thermocouple/temp sensor.

About 10K ago, I was getting 4d16 faults and they ran the fault tree and replaced the NOx sensors. $1800 or so. That fixed that problem, which actually started around 94K miles and gave intermittent faults, which I reset a few times with my BavTechnic tool until it became non-intermittent.

I'm living for the day I get another one, as it will be the SCR Catalyst.

Here are several related threads, including a couple on replacing DEF Container parts.
http://www.bimmerfest.com/forums/sho...d.php?t=756934
http://xemodex.ca/ca/product/scr-con...eturn-for-bmw/
http://www.e90post.com/forums/showth...2#post20485362

[Yozh]

floydarogers, wasn't some of the issues attributable to a bad thermostat?

[floydarogers]

Originally Posted by Yozh

floydarogers, wasn't some of the issues attributable to a bad thermostat?

You're right, I forgot to put that in. My thermostat was found to be bad (resulting in a 80C coolant temp) after they replaced the NOx sensors and that didn't solve the problem. Since the exhaust temp was a bit low, the SCR Catalyst never lit. So that would be item 3B.

There are probably a few other conditions that could contribute to 4d16 "DENOx Efficiency"

I'll edit my post. Thought of another thing they check.

[Yozh]

I just thought that was a great find of yours that has quite a bit of weight.

[octalon7]

Thanks for all the replies everyone. This is a frustrating item for sure it sounds.

m3driver999: wasn't aware of a software update either. I suppose I should look in to that as well. I purchased this car used less than a year ago.

greck: Thanks for the explanation, on how the code trips. Follow on question would then be, why would the code only trip once and then go back to normal operation? If there was something truly building up causing issues, wouldn't the code persist?

floydarogers: Wow you really have done a heck of a job researching and putting this all together. I only have a basic OBDII scanner that pulls the P20EE code, but my indie obviously has a better scanner. Last time I stopped by, they cleared the 4D16 along with 46A4 (didn't catch what exactly it was). I had no clue the DEF tank was such a costly part! Wow!

[Greck]

Originally Posted by octalon7

greck: Thanks for the explanation, on how the code trips. Follow on question would then be, why would the code only trip once and then go back to normal operation? If there was something truly building up causing issues, wouldn't the code persist?

I guess that even outside factors like cold weather, bad fuel, driving style(aggressive/retired), driving conditions(streets\freeway) can affect it, but in any case all of the above - are not a root cause, but they can explain why it is not stable...

[octalon7]

I wonder aside from the service engine light, if the actual emissions would not pass real testing.

[Barmlot]

To answer OP's question, in my case it was getting a new DEF tank (thankfully under warranty). As the dealer was troubleshooting I believe I got a NOX sensor too. The old tank had a bad level sensor and being under warranty I didn't want to putz around with trying to fix it myself. This was a while back when i was told by dealership that the tank was a "new part". I think they just switched manufacturers of the tank as there were many quality problems with original tanks.

[octalon7]

Originally Posted by Barmlot

To answer OP's question, in my case it was getting a new DEF tank (thankfully under warranty). As the dealer was troubleshooting I believe I got a NOX sensor too. The old tank had a bad level sensor and being under warranty I didn't want to putz around with trying to fix it myself. This was a while back when i was told by dealership that the tank was a "new part". I think they just switched manufacturers of the tank as there were many quality problems with original tanks.

Thanks. Glad you were able to get that done under warranty as it sounds extremely expensive. My issues started coming up after 70k miles so I am out of luck there. I do have a third party warranty now (Route 66), but they don't cover any of the emissions equipment afaik.

[floydarogers]

I was just reviewing my 335d maintenance log. Here's the timing/mileage.

1) The EGR/SCR/DDE update recall was done in 3/23/2012 at 48K miles: replaced the Mixer and Metering valve. The had to replace the Metering valve again about 11K miles later because it failed. Not sure if that replacement was under parts warranty or the WA State California Emissions warranty.
2) I had another CEL at 60K/61K, don't have code noted but probably 4d16/20ee, they replaced the Mixer (again, not sure which warranty covered it.)
3) Again at 74K, they said that the Mixer had been put in backwards... No charge... Came back on but I refused further work, AND IT WENT OFF until:
4) At around 89K/94K it came on a couple times; again reset and it went away, until:
5) Beginning at 106K when the NOx sensors were replaced, and the thermostat replaced. And of course at 115K the DEF tank was replaced.

Conclusion: you can ignore 4d16/20ee for quite some time (as long as you're prepared to reset the CEL occasionally and wait for a "hard fail".
I totally understand (but don't totally approve) of the reasons to rip the emissions stuff out: I've spent around $7K on the NOx reduction stuff.

BMW needs to actually fix their system, it's far too expensive. No wonder VW decided to cheat.

[octalon7]

Originally Posted by floydarogers

I was just reviewing my 335d maintenance log. Here's the timing/mileage.

1) The EGR/SCR/DDE update recall was done in 3/23/2012 at 48K miles: replaced the Mixer and Metering valve. The had to replace the Metering valve again about 11K miles later because it failed. Not sure if that replacement was under parts warranty or the WA State California Emissions warranty.
2) I had another CEL at 60K/61K, don't have code noted but probably 4d16/20ee, they replaced the Mixer (again, not sure which warranty covered it.)
3) Again at 74K, they said that the Mixer had been put in backwards... No charge... Came back on but I refused further work, AND IT WENT OFF until:
4) At around 89K/94K it came on a couple times; again reset and it went away, until:
5) Beginning at 106K when the NOx sensors were replaced, and the thermostat replaced. And of course at 115K the DEF tank was replaced.

Conclusion: you can ignore 4d16/20ee for quite some time (as long as you're prepared to reset the CEL occasionally and wait for a "hard fail".
I totally understand (but don't totally approve) of the reasons to rip the emissions stuff out: I've spent around $7K on the NOx reduction stuff.

BMW needs to actually fix their system, it's far too expensive. No wonder VW decided to cheat.

Ugh, stories like this make me rethink buying this car. Wish my extended warranty covered any of that stuff.

[floydarogers]

I just wanted to add a postscript to this, because:
Since February, BMWNA has extended the DEF tank warranty on 335d vehicles to 10 years/120K miles (it had been on X5d vehicles only since April 2016.)

BMW also added an extended warranty (also 10Y/120K miles) on the NOx sensors. (There are other posts on these two changes, if you search.)

So, I got back my $3200 DEF tank replacement cost, and should shortly get back my $1300+ NOx sensor replacement cost. Too bad I'm now over 120K miles if something else breaks and they add a warranty...