run4mo: thanks for your thoughts. I'm not sure what might be the (functional) difference between the 1.2 EGR and the one you have. Assuming you're talking about your 1.4 Polo, perhaps it just has more 'throw'/lift to allow a greater volume of exhaust gas through, in proportion to engine cc. As for the plastic replacing the metal on the solenoid housing, cost-reduction?, dunno.

With regards VCDS, I'm sure if you know what you're at, there are multiple avenues to go down which will all help diagnose EGR issues, but I didn't/don't know a lot, and the guy with the gear had only just acquired it too. Come to think of it, with the benefit of hindsight, the fault code 17811 translates as 'control difference' for the AZQ engine. This would seem consistent with the ECU thinking "Hey EGR-valve, I told you to close, but your potentiometer is still telling me you're open, harrumphhh!"

Wino, with respect to engine sizing, I thought originally that the "6" "7" etc might indicate different gulping parameters - ie profile of plunger, and at that time I did download some pages from the Pierburg application catologue - really just to get some true facts that would let me buy from another source - ie Pierburg and not VAG device and so save some money. Now the numbering might just have become a bit confusing, I did, in ETOS, follow the "1.4" engine trail from early Skoda to late Ibiza/Polo wrt EGR valves - 3-off in total, then used the Pierburg application list to tie Pierburg numbers to VAG numbers - just so that I ended up buying the latest so maybe the best evolution of this valve.

The VCDS issue, well the first thing I noticed, after removing/fitting the original valve, was that the closed voltage value had risen from 0.948V to 0.987V after adaption, so I conveniently concluded that my gut feeling was correct and that the valve was not closing as well as it had done when first adapted to the engine ECU in the factory. Only a few days ago, after fitting the new valve did I find that it also had a closed value of 0.987V - fully open value of both valves was roughly the same though!

I am starting to think that a lot of these possible issues are really too tricky to nail down - especially at a dealership with high labour rates, it just seems that anything I do improves things - and that is in reality and not just "in my head" - MAP sensor swopping for used one and cleaning and maybe refitting old one. Mind you, my issue carries a different tag - ie "light and annoying pinking" - not like your original posting, after that I'm heading for fuel filter replacing - first time in about 10 years 85K miles - so that might end up with something breaking!

I've been on the case of beating these issues for about 8 months, probably prompted with the challenge of helping someone on the Polo site solve his problems!

Edited 12 July, 201213 yr by rum4mo