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Adblue

10K views 6 replies 4 participants last post by  pauluk 
#1 ·
Hi all
My Q2 30 tdi shows 4500 miles for the adblue on the onboard computer. On this basis I bought 10 lts at around 4300 miles. The mileage has now gone beyond 4500 and no top up warning has appeared despite the display still showing 4500. Am I misunderstanding something ? When can I expect the warning to appear ? I believe that I can't top it up until the warning comes on or else the system won't know that more has been added.
Appreciate any advice you can give.
Thanks
 
G
#2 ·
You're the first person I've ever heard worrying about the car NOT asking for Adblue. As I understand it, the car will only need Adblue when the DPF is becoming clogged. If you regularly do reasonably long journeys and the car gets up to a good temperature then you might not need to add any. Cars tend to guzzle the stuff when they are used for short, shunty journeys and the exhaust gases don't get hot enough to break down the harmful deposits in the DPF and chuck them out. I'm not a mechanic but this is my basic understanding. We've had cars that needed Adblue every 1000 miles and an oil change at every 6000 and then we've had cars that did 15000 and never needed Adblue. But what do I know? I drive a petrol now. :)
 
G
#4 ·
Weeder said:
Thanks for the advice. While I understand what you are saying my car does a regen fairly often so I assume this is an indication of the DPF blocking. Can't understand why the car gives you the mileage for a top up and then ignores it ?
If your car is regularly doing a regen I would have thought it WOULD have needed Adblue at fairly regular intervals, I know my hubby's Land Rover did. Diesels! Presumably your Q2 has got a warning sensor that will alert you when you actually need to put some in, but again, I'm not a mechanic and I don't have a diesel so take what I say with a pinch of salt. Maybe give the dealer a ring and just ask, to be safe. :)
 
#5 ·
My 2.0tdi hardly uses AdBlue. I do a few long long trips in her every 6months or so and the rest is around 15km a day. If it needs a regen then it does it and if it needs a run to do it properly then there is a yellow warning telling me so. The AdBlue goes down in 500km sections, not sure in miles but presume it's the same. Never had a problem. I fill up when the alert comes on which is 2000km to running out I think.

If your DPF was "blocking" then you would get multiple alerts and it would drive like a pig. I don't think you have a problem with it, take it on a run, get a good DPF regen done, fill up the AdBlue and see what happens.

BTW, the 4500m is the max range the AdBlue can do. It's like the fuel range for your diesel tank. One min it will register 500m to your full tank, floor it and it will use more fuel so your range goes down. But I think AdBlue has a max of around 4500 which would be 8000km which I think mine states when full.

Question for you: Why are you filling it up at 4300m left? Even my OCD isn't at that level. Let it go down and operate normally. Fill it up when alert comes on.
 
#6 ·
AdBlue has nothing to do with DPF.

There are two emission devices - SCR and DPF.
AdBlue is injected into SCR to help reduce emissions (google for more details about how this chemistry works).
Your AdBlue consumption depends from your driving style, type of journeys, etc.
DPF is a standalone exhaust device that captures most of the exhaust ash. When your car does a "regen", it means the engine management increases the exhaust temperature which then burns the ash build up in DPF. There's no AdBlue in action during regen.

If you read your Q2 handbook it's all explained there. The point of AdBlue is for owner not having to care or even think about it until the AdBLue fillup message comes up on your dash. When that happens you still have around 2500Km worth of AdBlue in your car.
 
#7 ·
10l is good for about 7500km on my 2.0TDI. The warning will show up when you have 2000km left (or 2500km, i forget which) and the lower it gets the more persistent the warning. Once you restart after a refill give it a few seconds to register the new level and cancel the warning.
 
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