Problems refilling adblue tank

[Joolz999]

Hey folks – be great if I can get some help/advice from the forum with an adblue filling problem.

 My GF has a 66 plate Q5 – she recently told me the adblue countdown message (which started at 1,000 mile to go) was saying 400 miles so I decided to do the refill assuming it was easy job ! Her records aren’t that good but we think it was last filled by her garage  around  Oct 2023  since which she’s done about 4,000 miles – of which quite a high %age are short journeys.

From the owners manual, various forums etc I think the tank is 23L capacity and it should have used around half a tank, so I got a couple 10L Greenchem containers.  I’ve been fixing and mending me own vehicles for many years, mainly older cars  but I’m happy to tackle major jobs, cambelts, suspension work, welding up etc and thought this would be routine task.

However when I tried to fill using the standard spout that comes with the containers about 1L went in and then it starts to overflow up out of  the filler inlet hole and down thru’ the drain hole in the filler panel onto the drive. I tried inserting a thin tube to see if I could dipstick the adblue tank (and find out if there a non-return valve or other in the neck) – the tube went in ok (no valve I could feel) but the dipstick thing didn’t work (seeing the liquid was unclear). I then tried decanting the adblue into a smaller bottle and pouring it in (slowly) using the supplied spout as a funnel (it seemed like there could be an airlock problem with the 10L containers given there’s no air-admittance function) - but the same overflow thing happened and I couldn’t get anymore in.

After that I switched the ignition on & the 400 mile msg was still there – then it switched off and started and ran the car & the same msg still present.

I read the Q7 has a two tank system with one of the tanks being higher than the filler which has caused filling issues but no one says this is a Q5 problem. The manual refers to a “hose” to screw to the container (which defo looks longer than the supplied spout) but I’ve seen youtube vids of people happily filling a Q5 using exactly what I had  – i.e. a 10L container with the supplied standard spout.

I guess the obvious problem is a failure of the warning system/sensor – but it has counted down the miles in a sensible fashion. Online info indicates 9,000 miles per 23L tank – so at 4,000 miles I was  expecting the system to be around half full and thus to need about 10L ?

So frustrating that simple tasks are problematic on far too many modern cars…….

Thanks for any input

Cheers

Joolz

[Steve Q]

Common problem on vag cars is that the sensor doesn't reset. You'll need to get a diagnostic check to see if any fault codes flag up. 

Quite a lot of threads in tis already. 

[Joolz999]

Steve - thanks for speedy reply 

Yes I did see some threads on sensor failures -  just didn't think they were likely relevant. I mean as far as I understand the sensor reset the system last time it was refilled (i.e. the prev warning msg in Oct 2023 disappeared when it was refilled) and the msg it reappeared recently which seemed to makes reasonable sense - so didn't have sensor as prime suspect.
But what's really puzzling is by sensible calcs the car should have used around half a tank since last refill yet I could only put in a very small amount ?   I find it hard to credit that Audi would design the system so that a failed sensor is supposed to prevent the tank from being filled ?  And further I wouldn't have thought a sensor failure would even be capable of preventing refilling ? 
I like to try & understand what's going on and why - but of course - it will likely have to have some diagnostics to see what's flagged.
Thanks

[Steve Q]

Unfortunately manufacturers haven't seemed to grasp how to calculate the usage etc. which is daft twhen they've been able to do with with petrol/diesel tanks for decades. 

On some manufacturers it's based on how many times the fuel filler flap is opened. 

It'll need a diagnostic check to see if any fault codes flag up 

[KevinAudi80]

All signs in the sky indicate that there has been a problem with the AdBlue pump. Obviously I would still try restarting it, once the fluid has been topped up, switch on the ignition and then the user should wait for about 30 - 40 seconds, this way the message will clear.

[Joolz999]

Thanks for input guys - just to follow up - GF took car to garage and the guy there  managed to glug in another 2 litres or so (same container, same spout) - he thinks it's now full and the warning msg has cleared itself. She even took a video which showed him doing the same as me ?!
So I'm left almost as confused as when I started - although around 4/5 litres for 4,000 miles sounds about right.  Maybe it was an airlock in the tank that needs a bit of driving to clear it ?
So far the worst of it is a slightly bruised ego - which is a lot cheaper than a sensor replacement I guess !

cheers

[Steve Q]

Glad you got sorted 🙂 

If it's any consolation I get my wife to take her jaguar to have her xe adblue topped up, as jags are known for adblue system issues. This has saved us twice when the system has gone faulty and they've had to drain the tank, reset the sensor and top it back up FOC twice. 

My rationale is, if they do it then we can't be blamed for it being over filled or wrong adblue fluid added etc. 

[Sofa]

Easiest way to re-fill Adblu is to use the pump at a Petrol Station,there are two different nozzle types,I prefer the shorter nozzle with the lance type handle for ease of use. I’ve had similar Adblu related experiences,in several years use I’ve re-filled tank with varying amounts ranging from 2L to 20L when light has come on/counting down. Using a new 10L container of Adblu is awkward to hold at required level while getting flow rate correct. Try the pump,you’ll not regret it,plus works out cheaper per litre for me