Repeated P0401 means cracked DPF?

I recently purchased a 2010 Jetta TDI with 124K miles. Shortly after I bought it, it started showing a P0401. I took it to a import diesel mechanic in my area, and he said to replace the EGR filter. I had him replace the EGR Filter (as well as the timing belt). After he replaced it, he told me that it had been replaced before.

The P0401 light went out for about 600 miles or so. Then it came back on! From my reading on these forums (great, by the way), it seems like my real problem may be a bad/cracked DPF Filter. I'm guessing that this P0401 light means that my EGR Filter is clogged again.

Can anyone help me with next steps? I bought a VagCom, but don't know how to really use it to get soot levels that I may need.

I hate to take it to the dealership, since I've really invested quite a bit in the car already.

One last note. My fuel economy seems to be less than I expected. I'm getting about 36 mpg in mixed driving. Otherwise the car seems to run very well, and has surprising low end power. Any help would be very much appreciated!

Check out the DPF data collection thread over in the Emissions forum for details on how to get that info (and enter yours!) -- http://forums.tdiclub.com/showthread.php?t=324067

I noticed some P0401 codes recently as well. Haven't checked them again yet, and I don't have a check engine light. I presume you don't either. I'm getting 36-ish MPG as well, and always have for the most part.

I am noticing a tad bit of soot at my tail pipe -- is yours totally clean or does it have some? I'm wondering if I've got a cracked DPF. My ashload is not excessive -- 150ml.

In short, it's possible you've got a cracked DPF. EGRs getting clogged up can also be caused by a flapper valve not working correctly -- I suspect the majority are probably due to this vs. a cracked DPF. I think there's a VW service bulletin that's been out for a while on issues with this valve, and they've been installing a newer version of it I believe. If you search for 'P0401' you'll see threads discussing this.

Do you have soot in the tailpipes?

Thanks for the replies. I do have the CEL on. I get two codes when I run it from my VagCom, P2015 and P0401. I think it's the 2015 actually triggering the light.

I haven't checked my tailpipe yet, I check it tomorrow morning and report back. I'll also find out what my ash load is like.

Which flapper valve do you mean? I'm having trouble with my intake flapper (I think that's the P2015).

Thx again

There's a TSB (Tech Service Bulletin) about the exhaust flapper valve and coverage for it being extended to 120K miles -- http://forums.tdiclub.com/showthread.php?t=379543

Looks like there's different, specific code when it fails (P047F). For some reason I was associating it with the P0401. If you're not getting that other code then it's probably not the issue.

rtstephn said:

Thanks for the replies. I do have the CEL on. I get two codes when I run it from my VagCom, P2015 and P0401. I think it's the 2015 actually triggering the light.

I haven't checked my tailpipe yet, I check it tomorrow morning and report back. I'll also find out what my ash load is like.

Which flapper valve do you mean? I'm having trouble with my intake flapper (I think that's the P2015).

Thx again

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The 36mpg is normal for mixed. Mid 40's is normal highway at speeds at or above 65mph depending on load and ambient temperture.

You have two problems, you need a DPF and the EGR filter tube (problem one, for the P0401 EGR insufficient flow), and you need an intake manifold (problem two, for the P2015 intake runner fault).

Both getting pretty common now.

oilhammer said:

You have two problems, you need an intake and the EGR filter tube (problem one, for the P0401 EGR insufficient flow), and you need an intake manifold (problem two, for the P2015 intake runner fault).
Both getting pretty common now.

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Thanks OilHammer. I understand about the intake manifold, but can you help me understand the intake you mentioned for the P0401?

Are there aftermarket EGR Filters? This would be my third EGR Filter. This is why I'm starting to suspect a cracked DPF.

I checked my exhaust today by swiping my finger inside the exhaust. My finger came out black. I used to own an old Diesel Merc 240D, and that was normal for that car. What is normal with these TDI's as far as dirty exhaust and a potential cracked DPF? I hadn't noticed the dirty exhaust until I put my finger inside it. I don't notice any smoke at start up or hitting the gas hard.

Sorry, edited my post. I meant DPF for the P0401. TSB for it, becoming quite common now.

DPF cracks internally, causing soot to get past. Soot not only gets to the tailpipes (which should be spotless clean on your car), but also gets into the little filter/catalyst pipe going to the low pressure EGR. That little pipe clogs shut with soot, then no more EGR flow happens, and thus the P0401 sets. So, the clogged pipe is the immediate cause of the EGR flow concern, but the root cause is the cracked DPF. You can put a new pipe on there (~$240 part) and a few months later it'll be clogged up again unless you also install a DPF.

Luckily, on the 2010+ cars, this means just a DPF and that pipe. On the 2009 cars, it means upgrading the whole exhaust system.

I'm going through the same thing on a 09 JSW. I can't tell if I can use a 2010+ DPF, ERG filter, NOx and valve. Will the later model DPF and related exhaust components fit the 09?????

My '10 is at 145K and the P0401 comes and goes (since 80K). No other codes.
Need to figure out if I have a cracked or a clogged/full DPF. Or maybe just the sticky EGR valve issue.
When you say "You need a DPF" - do you mean a replacement DPF? or a DPF cleaning? Has anyone priced or done the following:

- replace a cracked DPF (w/o VW help)
- replace a filled-up DPF
- clean a filled-up DPF

If this is in the thousands of $$s, I feel that VW touted the clean diesel feature, but did not worn about the price of maintenance (I want my A3 Jetta back!). The hard part of this is justifying this kind of money on a car with 125 - 150K miles on it. You sort of have to commit to keeping it for the next 125K, yet you will not recoup this cost if the car is totalled.

I am also curious if this maintenance applies to TDI's with Urea injection and at what mileage intervals. How about non-VW clean diesels - BMW/Mercedes - how long do their DPF's last?

http://www.myturbodiesel.com/threads/garage-cleanup-sale-2010-jetta-tdi.26484/

I think the newer parts will fit.

might be worth a drive north to pick up a used set, or perhaps find one closer.

ellis said:

I'm going through the same thing on a 09 JSW. I can't tell if I can use a 2010+ DPF, ERG filter, NOx and valve. Will the later model DPF and related exhaust components fit the 09?????

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The later model system will work for you no problem