AdBlue misery

[timhowarduk]

Hi
I'm the new owner of a 2011 Alhambra with about 96k on the clock. Lovely car. But...
Driving back from Scotland it flashes up "Check Adblue car will self destruct in 650 miles" or similar. By time I got home it was down to 500 miles.
So, just topped up with AdBlue as per the manual, it took about 9.5 litres before it was full. I noted this was less that the minimum 10 litres stipulated in the manual. Then as per manual turned ignition on, waited at least 30 seconds, turned engine on.
So, the warning remains. I've now searched around forums and realised that it sounds like I have the dreaded and potentially expensive AdBlue NOX sender problem.

I'd appreciate any suggestions or stories of similar experiences and what the problem turned out to be. Also some specific questions please:

1-I'm about to get hold of VAG K+CAN Commander as I need to reset an airbag error caused by removing glove box to fix fan. Will that software help at all with proving the cause of the issue?
2 - I've read that cleaning the NOX sender is a sensible first step. Is anyone aware of a post detailing how to get to it and remove it. Instructions are always nice! I've got some workshop manuals but they omit this detail.
3 - I've also read that a software upgrade might help. Is there a way to find out whether it has the latest software?

Thanks for any help. Tomorrow I'll be chatting to the used car dealership I got it from and attempting to make this their problem.
Tim

[Crasher]

Personally I would suggest VCDS, I have tried a lot of VAG specific systems and VCDS is still the best.

Typically the system takes a lot more than 9 Litres, one I did the other week took 12.5L and that was a day after my colleague had finished off what we had in stock which was about 3L. The dry capacity is 18L.

You may need the repair kit part number 561198969 but at £443.50 I would wait until you have diagnosed it properly and I have known the system suddenly reset.

[timhowarduk]

Thanks - I can see VCDS being useful over the life of the car so probably worth shelling out the extra cash. However the immediate need has gone.
As an update, the dealer (non Seat) I got it from has agreed to help and lent me a car while they look into it. They cleared the airbag fault for me and they later spoke to a Seat dealer (Wrexham I think) who suggested that the reason that after 9.5L it appeared full was due to an air pocket and when they dip the tank they reckon it isn't full, therefore trying again to fill it is the next step.
I personally don't buy that, however I'll go along with it to advance discussions and am taking more AdBlue to the dealer tomorrow morning to prove the point. They did say they are willing to dump the problem on the Seat dealer at their cost if the problem persists, so this is probably just a patience game now.
My own opinion is that it's more likely one of the Nox sensors, the pump or the injector and until Seat plug it in for some diagnostic info it's anybody's guess which. We'll see!

[timhowarduk]

So this morning I demonstrated that it was indeed full, it took about 20ml before it poured out the top. So with no arguments it's going off to Seat on Thursday. In the meantime I'm driving about in this little go cart thing, Suzuki Swift I think!.

[timhowarduk]

It's had an ECU Recall and an Ad Blue Recall and this seems to have fixed the problem. Hopefully this will remain the case!

[timhowarduk]

Well, the problem is back. "Check AdBlue". Tank full again. Since last time I've bought VCDS. Fault codes:

Chassis Type: 7N-VW36 (7N0)
VIN: VSSZZZ7NZBV512733 Mileage: 158150km-98269miles
9567 - NOx Sensor 2 Bank 1
P229F 00 [039] - Implausible Signal
15733 - SCR NOx Catalyst Bank 1
P20EE 00 [101] - Efficiency too Low

So far I have removed Nox Sensor and cleaned it. Then ran "Reset SCR Lock" and "SCR Efficiency Check" in VCDS which failed.
Then I pulled AdBlue injector off, it seems clean, and then ran "SCR Metering Test" from VCDS and can see it squirt which I'm taking to mean that the system is basically working.
Currently waiting for replacement Nox Sensor to arrive, will try fitting that and really hope that fixes it as I'm currently out of other ideas. Anyone had anything similar?

[Crasher]

I imagine you will be fitting the updated part 03L 907 807 AE at £443.32?

[timhowarduk]

Actually was going for a 2nd hand 907807 C with a years guarantee and 30 day returns for £90....
Is the updated part significantly better?

[Crasher]

No that is not a good idea at all, used emissions sensors don’t make sense.

[timhowarduk]

No that is not a good idea at all, used emissions sensors don’t make sense.
Ok, thanks.

[timhowarduk]

Fixed! Replaced sensor (new as advised). Then took car for a drive to get up to temperature, and then in VDCS I could run the SCR Efficiency Test which passed, and message went away. Thanks for help.