Help!!! P0401 code comes and goes !!!!

From 1700 miles I have been getting this code off and on of course when I brought I to the dealership it was off so they won't do anything ! When I called to make a second appointment I told them what code I was pulling and booked an appointment in 2 weeks from now !!! I asked them if it is safe to drive the car and they said yes it's fine.... The car is running fine but my concern with an EGR problem is if it can have any effect on the dpf?? I don't want to set myself up for an expensive repair in the future especially since I have a feeling that when I bring it back and the light happens to be out they won't do anything about it ! I guess my time bringing my brand new car to them over and over again for an intermittent problem doesn't phase them ! Any info would be greatly appreciated !! Thanks

the codes stay in the ECU until they are cleared, don't clear the code and then the dealership is forced to repair/replace anything thats wrong.

I don't plan on clearing the codes but the first time it came on for about a half hour the dealer said nothing was stored... My big worry is if driving with a stuck egr valve can damage the dpf causing problems later (post warranty) ???

dealer lied, it wasn't the first time in history, stay on them.

Had a similar issue caused by a cracked DPF (internally), Low Pressure EGR was also replaced in the process. Seems to have fixed it so far (only been a month).

Thanks guys this gives me something to talk to the dealer about when I drop it off ... Just hope they don't try and give me the runaround again !!

When we had the ECU update this spring the EGR instantly flashed the P0401 code and ended up being toast = Warranty RE & RE of the EGR valve.

Update !!! Just got my car back and the dealer replaced the dpf and removed and reinstall egr cooler .... They said the filter was clogged !!! After only 3500 miles ? Any underlying causes why this could have happened ? It was all fixed under warranty and I was given a loaner for the week w/o my car soo all is good but I'm still a bit confused on how this could happen soo soon ....

Our car is showing this code also. It has just over 40k on it now, and just over a year old. I'm worried that this is out of warranty due to the miles, but maybe since it is emissions that it will be covered?

So seems the DPF is a problem on these cars also as these threads are popping up every other day. Good thing they are covered under warranty.

Dealer replaced DPF under warranty, 45k or so miles. Light on again about 1k miles later with the same p0401 code. Took it to the dealer again, this time they said it was the EGR and it would need to be replaced, not under warranty. They said $500+, I said put it back together.

I am really beginning to dislike this car

Egr valve is covered under the 80 k federal emissions warrenty I would imagine ? You can always try and clean it too

I had a cracked DPF on a 2010 JSW with only 7500 miles on it - P0401 code -- It took four months of back a forth trips to the dealer to finally diagnose and correct the fault.

Service first initiated DPF cleaning cycles for awhile, and when that didn't correct the fault they replaced the EGR, and EGR boost pipe, then the central wiring harness was repaired, wires were repinned at EGR connector, at one point techline involved and computer was "reprogrammed"....the CEL remained intermittent and at one point there was a flashing glow plug indicator and the car went into limp mode.... Luckily I was not far from the dealer and got a loaner.

Final outcome; four months from when the error first appeared the DPF was found to be cracked and the DPF along with the catalytic were replaced under warranty. That was back in May of this year and so far the CEL has remained off. Looks like there may be a few faulty DPFs out there.

I had a P0401 back in Sept 2014 at 102k miles. Two dealerships seemingly without more diagnosis than what I assume was plugging in a Scantool and noting black soot on the inside of the tailpipe recommended the $2900.00 DPF replacement. I went to a local Independent TDI shop in Western MA and had a mildly used (under 3000 miles) Engine to tailpipe swap performed for about $1300.00. The tech thought that a complete swap would be easier than opening a can of worms by trying to diagnose individual components of my emissions system.

Now in Sept 2016 at 133k miles the P401 as well as the soot in the tailpipe has returned.

Seeing that the p401 was somewhat Intermittent (Weekly) and that I have heard that a cracked DPF still works even though it throws codes I wonder if I should have just ignored the issue all along. Now that there is Dieselgate I feel even more strongly.

One side question. My P401 is preventing my passing inspection. At first I went through inspection without even checking readiness on my Scantool. After driving 400+ plus miles all fields are back to green. Will the P401 also disappear on its own or do I need to clear the fault codes and then drive another 400 miles hoping the P401 (EGR Filter??) does not flash again?

(I do have VCDS but leaving my Scantool LX connected to my Smartphone has been more convenient)

From what I understand, in my state of Massachusetts I have 60 days to pass emissions after I fail.

Thx,

Pete

SmokeyPete said:

Now in Sept 2016 at 133k miles the P401 as well as the soot in the tailpipe has returned.

Seeing that the p401 was somewhat Intermittent (Weekly) and that I have heard that a cracked DPF still works even though it throws codes I wonder if I should have just ignored the issue all along. Now that there is Dieselgate I feel even more strongly.

One side question. My P401 is preventing my passing inspection. At first I went through inspection without even checking readiness on my Scantool. After driving 400+ plus miles all fields are back to green. Will the P401 also disappear on its own or do I need to clear the fault codes and then drive another 400 miles hoping the P401 (EGR Filter??) does not flash again?

(I do have VCDS but leaving my Scantool LX connected to my Smartphone has been more convenient)

From what I understand, in my state of Massachusetts I have 60 days to pass emissions after I fail.

Thx,

Pete

Click to expand...

http://forums.tdiclub.com/showthread.php?t=445921

(if you have not seen)

Pretty sure you need to reset the codes to get the MIL out. (they should reset on their own after 255 test cycles in a row without error, but it is a bit of a mystery how often exactly, and what conditions let the car run whatever test sets the P0401 error for LP EGR)

then, as you know, driving till the car runs an active DPF regen is needed to clear the readiness for emissions.

My MIL came on, and I went through a couple clear and watch it come back cycles.

should be plenty of time to get the codes reset, and get through emissions tests. key is knowing what is going on, and the VCDS is the right tool for the job.

I suggest driving till you see 15 g or so of calculated soot, reset codes, and starting with a cold start, drive till the regen runs and you have cleared all readiness, and then drive directly to an inspection location, without letting the car cool down.

( I have not reset codes on my car with it warm and watched for all the clearing of all pending emissions checks, but think at least a couple require cold start.)

Just a quick update. Despite having the MIL on I drove my TDI about 400 miles until all of the readiness indicators turned green and the MIL disapeared. Even though I still had a stored P401 code, I passed my MA State inspection.

i've had my DPF replaced once already and now its cracked again, i just keep clearing the code untill VW buys it back