HELP with A3 1.9 Tdi - Starts but stops (EGR P0401)

[ShahAli]

So, needed some help.

I have a 2008 A3 1.9 tdi Manual - Services regular, camblet, Clutch, master slave cylinder etc all replaced in time. Do long drives and when the DPF light comes, when engine is hot i drive 4th gear 50MPH with revs around 2500 and this then clears it after 10 mins or so. 

over 2 weeks ago i noticed when driving occasionally i can feel a rumble. Lasts a second so i thought i was imagining it. 

2 weeks ago as i was driving up a hill and i noticed that the car was not climbing so i went into lower gear and felt that was not helping so called RAC and lifted back home.

SYMPTOMS:

Car comes on, engine comes on but the revs are limited. When i go into gear and try to go faster than 5mph the engine cuts out.  Same in reverse as well. As soon as i increase the throttle the engine cuts out. When i don't engage the car i can rev it but i think it limits hte rev to around 2000 or so. 

RAC did diagnostics and came with 2 faults:

1)  P0401 - EGR flow insufficient

2) P0473 - Exhaust Pressure Sensor High

My local mechanic is fully booked and i'd need to tow it. I called a "reliable" and rated mechanic and have already purchased the parts from Germany ( EGR Valve and the EP sensor) .. the chap was supposed to come today having told him what i think might be going on.. but has let me down.

 

I've seen videos and basically the job is not difficult (besides one screw) - below is the actual job - Its a gold but same as my audi in terms of the part.

 

 

My Question:

1) Do you guys think it will solve the problem and does what i say happened fit with the fault. 

2) I don't have a VAGCOM - If i were to replace then would i need to just "ADAPT" the Sensor. What would happen if i did not adapt the sensor right away but say in a few weeks time having driven it. I say this because the VAGCOM and VCSD is about £250 or so, so would have to purchase this at a later date.

3) I thought in limp mode you can drive the care but not fast, mine seems to cut out completely. does that suggest something else?

 

Many thanks guys,

 

Sorry to ask for help, but i am sure a lot more people would know more than me here.

 

 

 

w

[cliffcoggin]

Shah.

1) There is a good chance, but no certainty, that a new EGR valve will cure the problem. It depends how far the soot accumulation extends.

2) I don't know what you mean by adapting the pressure sensor.

[Stevey Y]

1 hour ago, cliffcoggin said:

Shah.

1) There is a good chance, but no certainty, that a new EGR valve will cure the problem. It depends how far the soot accumulation extends.

2) I don't know what you mean by adapting the pressure sensor.

Hi Clifford, ref 2 when fitting a new emissions part you have to do a re adaption of the part so the ECU knows the part is new and will let it relearn its values when it should open and close, if you don't do this the ECU will reject the new part as the only values it has stored are for the the old redundant valve, you used to be able to not relearn on Fords and after a week it would sort itself out but I have found with VAG models they won't have any of it.

Steve.

[ShahAli]

Hi Stevey and Clifford,

Many thanks for your response. I have found away to get the 3rd nut off with a small extension and a spanner to twist the extension to unscrew the 3rd EGR valve.

Ideally i'd pay the mobile mechanic but this chap has let me down twice. I waited all day today and only when i chase him he says sorry and may be next time. So as i have the part and know how to de-assemble with the bit i created,  i'll do that over the weekend.  

My questions is, if i replace the EGR valve(i think i can reset this via my simple bluetooth OBD with Torque pro) and also the Exhaust pressure sensor, then i don't have access to the VAGCOM/CAN link until a few weeks later. Is it ok to "drive" the car and can i "ADAPT" the sensor later when i have the cables and software?  I've read a few people who in some cases inserted the sensor the wrong way round and were driving it for a while with funny VCDS readings (Negative values), but were able to drive the car. 

My wife say's i won't get answer's here as normal people just leave it to the mechanic. I suspect she may be right but you can learn a lot from youtube and forums! 

[Stevey Y]

22 hours ago, ShahAli said:

Hi Stevey and Clifford,

Many thanks for your response. I have found away to get the 3rd nut off with a small extension and a spanner to twist the extension to unscrew the 3rd EGR valve.

Ideally i'd pay the mobile mechanic but this chap has let me down twice. I waited all day today and only when i chase him he says sorry and may be next time. So as i have the part and know how to de-assemble with the bit i created,  i'll do that over the weekend.  

My questions is, if i replace the EGR valve(i think i can reset this via my simple bluetooth OBD with Torque pro) and also the Exhaust pressure sensor, then i don't have access to the VAGCOM/CAN link until a few weeks later. Is it ok to "drive" the car and can i "ADAPT" the sensor later when i have the cables and software?  I've read a few people who in some cases inserted the sensor the wrong way round and were driving it for a while with funny VCDS readings (Negative values), but were able to drive the car. 

My wife say's i won't get answer's here as normal people just leave it to the mechanic. I suspect she may be right but you can learn a lot from youtube and forums! 

Hi not sure about Tourque Pro but I know you can use OBD11 that works, I must admit what your wife said about this site made me smile, thats why your mobile mechanic has not appeared as with the right tools its a simple job but the thing that scares him is the relearn, I suspect its a bit above his pay grade, this site has helped many people and we have given you the correct information to complete the task which begs the question, why ask the site.

Steve.

[ShahAli]

So with my own self made adapter tool took off the throttle thing, then managed to get the EGR valve off. took a bit of time loosening it but wd40 did the trick along side gentle nudging for 10 mins!

Will clean the throttle valve today and install the new EGR valve and also sensor.

Wont be able to ADAPT any of those but hoping car will start and run and can adapt later. Lots of reading on net some suggest car self adapts etc.

The EGR valve compared to the new one was about 85% blocked. Just had a pencil hole gap in it. Hoping this is the issue.

 

I was disappointed at the mechanic. Wont post details but his review was good and also 10 mins drive from me. Does Clutches and other repairs so i have no doubt he is good and knows his stuff but just not hungry enough for the job.

[ShahAli]

Always good to update people incase it helps others.... So here goes.

1) I replaced the EGR. Relatively easy to do other than the 3rd screw. Had to use the trick the chap in the video used. 

2) Cleaned throttle body.

3) Changed the DPF Exhaust pressure sensor. This looked simple but I found it hard to pull out of the tubing. So I twisted it a little pulled it and then seems the smaller pipe off the sensor snapped inside the tubing! So using a bit of ingenuity I screwed a screw inside it and slowly pulled it out in 2 pieces!

4) Did not have VCDS to adapt the throttle body or sensor.. so just drove it...

 

5) there was a lot is smoke coming out after 15 mins engine warm and as I was driving it. I'm telling you it left a plume of smoke. I part expected it thinking may be some carbon deposit had fallen in as I had cleaned the hoses with a spoon to take the crud off.  Later DPF light came on.

6) Drove it for a good 5 mile run, doing 40 in3rd gear after engine warm to burn the soot out of the DPF. Seemed to clear it.

7) Got VCDS and cleared fault codes and adapted the sensor.

😎 STUCK.. could not adapt the throttle body. Kept saying error module not found. Spent half a day internet searching and no one has the same adaptation problems as me. They all input code 060 and "do it" and it's done! 

9) seems Deisel engines don't have a "throttle" as in petrol engines. Although same thing, TDI ENGINES do not need adaptation. Diesels use the throttle more for air flow and also stopping the car than for throttle! 

10) DPF light off and car seems to work fine now. 

11) At 133k I'm now waiting for the turbo to go someday. I'll probably have to get a pro to do that job! 

 

Thanks all.

[Stevey Y]

Hi the reason you could not adapt the throttle body was that the ECU already had the values for that body, with regard to diesels not having a throttle I would beg to differ it works exactly the same as a petrol driven car the wiring plug on the side transmits the voltage to the throttle body from the pedal when you push it down so it knows how far to open the butterfly to acellarate or de acellarate, wherever you got this information is very wrong, glad you got it sorted in the end and tell the wife, see you can get the answers from here and save a few bob on labour.

Steve.

[ShahAli]

i think what i meant was a diesel does not need to have the throttle body adapted as do petrol ones. That is the reason why VAGCOM did not find the value of 060 that i was searching for. You are right in that that the "throttle" body is just that, looks exactly the same as a petrol one with the butterfly but from what i read it said the throttle body is used in petrol to regulate the air to inc or decrease acceleration, in diesels this is done by injecting more or less diesel.  Having said that, that does not make much sense as you would still need to regular the amount of air going in!

I suspect you are right and either what i rad is nuance or incorrect. Regardless, made me happy that i could not find something because it did not exist.

Wrt the ECU having the values, would that not be the same for petrol cars,.. and if so then why the need to adapt?

To be fair the car drove well without me adapting the exhaust pressure sensor, so it may be just something we do but not really needed to be done.