User Tag List

Thread: P401 Error Code - 1.9TDI EGR Valve diagnosis, cleaning. Plus Black box valve manifold noise

Results 1 to 1 of 1
  1. Question P401 Error Code - 1.9TDI EGR Valve diagnosis, cleaning. Plus Black box valve manifold noise 
    Join Date
    Dec 2013
    United Kingdom
    Post Thanks / Like
    0 Post(s)
    0 Thread(s)
    0 Post(s)
    Hi All,

    I hope someone out there may have the answers to my questions

    Car: Seat Altea 1.9TDI (55 Plate)
    EGR Valve: Diaphragm type (part No: 038131501AF)

    The problems started when the 'Emissions Workshop' warning and engine light came on a few weeks ago.
    After buying a code reader I diagnosed a P401 fault code that related to 'EGR insufficient flow'

    I saw that you could test an EGR valve at engine idle by applying a vacuum to the diaphragm and the revs would drop/come close to stalling. I rigged up an air cylinder and tube to create this test and nothing happened which made me think that the EGR wasn't working, but then was my vacuum too weak? Or did I not know enough about the type of EGR valve it was?

    Then following searching on forums I decided it was worth taking the EGR valve off and having a look. There was grime/small bit of oily residue within and around the pintle shaft, carbon build up on the bottom of the pintle where the exhaust inlet connects and some oil looked to have been leaking from a vent hole beneath the diaphragm and out onto the rear of the engine.

    I cleaned it up with carb cleaner and scrubbed it accordingly. re-assembled and cleared the fault.

    I half expected the fault to return and it did.

    Then I also identified another issue that could be the problem and not the EGR valve at all. There is a block box valve manifold which feeds the vacuum to the EGR valve and when the engine is turned off this box vibrates and makes a wheezing noise for 3-5 seconds. it is obviously an issue and my wife who drives the car said that the noise has been about before the fault appeared, so that could be it!

    Finally I did some more research on EGR valves and discovered that there are positive back pressure EGR valves that require at least 2000rpm before the valve can be opened by the vacuum. this is achieved by exhaust gases travelling up the pintle shaft to push on a second diaphragm. So I'm thinking that my test was incorrect and that I didn't clean the valve properly because I didn't look at clearing the inside of the pintle! and I want to eliminate the EGR valve as the problem part. So now I'm thinking restrip and clean the EGR in particularly the inside of the shaft.

    So to recap on what would be helpful if anyone knows the answers

    1. Is this VW EGR Valve a 'positive back pressure' type?, i can't find out on google! i.e. is there a hole in the pintle shaft that you need to make sure is clean through? (picture of the bottom of the EGR below which I thought I cleaned.
    2. How can I be sure that I have applied enough vacuum to the EGR valve to test it manually and discount it? can I temporarily route another vacuum pipe from the engine? If so which one would you choose?
    3. Is the noisy valve manifold containing the solenoid for the EGR valve the likely issue?


    Thanks, James
    Attached Images
    0 0 0

Similar Threads

  1. EGR Valve cleaning
    By jakerade in forum Audi A4 - B8 Forum - 2008 - 2015
    Replies: 3
    Last Post: 10-06-2014, 02:44 PM
  2. EGR Valve Cleaning
    By TDiBoraSam in forum Bora - 1998 - 2005
    Replies: 5
    Last Post: 31-05-2010, 08:12 PM
  3. EGR Valve and Manifold
    By SportAvant in forum Audi A4 - B6 Forum - 2002 - 2005
    Replies: 17
    Last Post: 25-11-2009, 07:55 PM
  4. EGR valve cleaning
    By inca66 in forum Passat - B5 Forum - 1997 -2005
    Replies: 1
    Last Post: 19-03-2008, 02:48 PM
  5. Cleaning egr valve
    By passat 130 tdi in forum Passat - Archive Topics
    Replies: 2
    Last Post: 10-02-2008, 11:50 PM
Tags for this Thread

View Tag Cloud

Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts


Disclaimer: VW Audi Forum is an "independant enthusiast website", administered in line with guidelines supplied by VAG in the UK, and is in no way related to any of the Worldwide Volkswagen,Audi,Seat,Skoda,Bentley,Bugatti,Porsche or Lamborghini group of Companies. For official up to date information on any of there vehicles, please visit the official websites. Any comments made throughout this website, are the views of the respective poster, and in no way represent the views of the VW Audi Forum Administration, or the worldwide Volkswagen & Audi Group of companies.

VW Audi Forum do not vet and are not responsible for any information which is posted in this forum. All content is viewed and used by you at your own risk and we do not warrant the accuracy or reliability of any of the information.

Copyright: Certain "words", "phrases" and "Images" used on this website by the Administration are "Copyright" of Volkswagen GB, Volkswagen AG (Germany), Audi GB, Audi AG (Germany), Volkswagen Motorsport GB, Volkswagen Motorsport AG (Germany), Audi Motorsport AG (Germany), Volkswagen Racing GB, Bentley, Bugatti, Porsche and Lamborghini. No image can be replicated by anyone WITHOUT the relevant Companies written permission.

All trademarks and copyrights remain property of their respective owners.

No part of the VW Audi Forum website or forum may be reproduced without written permission from the site administration


This website and forum are best viewed at a minimum resolution of 1024 by 768.


- VW AUDI Forum - The #1 Volkswagen (VW) Group Forum - Volkswagen (VW) - Audi - Seat - Skoda - Bentley - Bugatti - Lamborghini - Porsche - VW Audi Forum -

- - -