So I have been getting 2002 dpf low efficiency messages for a while, even though only 74k miles on the clock. It does quite a bit of around town driving which will not have helped things.

The first message i got was a dodgy diff pressure sensor. This model has a pair of these and so i swapped both and ran the necessary adaptations in VCDS.

 

I still get the 2002 errors, even though the car takes a regen just fine, reporting low soot.

 

Apparently, the 2002 error can be caused by the egr cooler becoming blocked. Hence when the exhaust flap closes and egr opens you get a high backpressure.

 

Today, I got another egr and cooler on ebay, and bit the bullet. It was a pig of a job but I swapped out the rear egr and cooler units although disappointingly the one that came out looked pretty clean.

 

This model also has a second egr and cooler mounted at the front of the engine. Does anyone understand the functioning of this? When doing the rear egr and cooler swap-out, I did notice that with the engine off the rear egr is closed but the front egr is open. Is this correct?

 

Anyway, sorry for the rambling post, but I am running out of ideas now and the 2002 error comes back a few days after cleaning/regen. I have some JML cleaning fluids coming in tomorrow and will try an in-depth dpf clean. Short of that, I am out of ideas.....maybe some kind of electrical fault????

Hi, the car has a high pressure EGR system which comes straight from the exhaust manifold, through a cooler and into the clean side of the turbo, the low pressure system is the bit you have replaced which takes exhaust gasses after the turbo/nox catalyst/dpf etc. also via a cooler and back into the intake.

 

If you think about it, the EGR valve you have changed is going to be quite clean because its after the DPF therefore its not going to get blocked up in my opinion. 

 

From reading the literature on these engines the engine favours the low pressure EGR more because it is cooler (with the exception of right after a DPF regen) cleaner and doesn't effect the efficiency of the turbo.

 

Have a read of this, it may give you some further ideas https://pics.tdiclub.com/data/517/820433_EA288.pdf

Edited 1 November, 20223 yr by SuperbTWM

Thanks for the link. That is really helpful!

 

Mine is a generation after that I think.....quite similar, but there isn't a single G505 it has a pair....... and some of the components at the back look a bit different. 

Really useful to know how it is all intended to work though!

 

 

On 02/11/2022 at 09:16, Johnricketts said:

Thanks for the link. That is really helpful!

 

Mine is a generation after that I think.....quite similar, but there isn't a single G505 it has a pair....... and some of the components at the back look a bit different. 

Really useful to know how it is all intended to work though!

 

 

 So you have 2 differential pressure sensors? if one if across the DPF what does the other one measure?

 

 

 

13 minutes ago, SuperbTWM said:

 So you have 2 differential pressure sensors? if one if across the DPF what does the other one measure?

Of the two ports on the sensor, one will be before DPF, and second port is open to atmosphere.

 

Then on other sensor, one goes to after DPF, and second port to atmosphere.

 

That's as far as I recall how my two G450 DPF sensors are hooked up, suspect the G505's are same.

I suppose with the introduction of the exhaust flap and other complexities it does need that other sensor for control. So far i'm lucky enough not to have to deal with the emissions side on mine yet. *touches wood*