AdBlue top-up issue (merge)

[Cuiken]

I've read the other posts on this subject but am still at a bit of a loss so please bear with me.

I drove 400 miles yesterday in our van and checked them adblue level before I left. It read 3000 miles of range remaining.

300 miles into my trip, the beeper sounds and dash lights up with the message that I only have 650 miles of adblue remaining (plus the no engine start warning). It asks for 2.25 gallons of adblue. By the time I've finished the journey I'm down to 550 miles of range.

So, today I nip out and buy 10l of adblue (2.2 gallons) and add that to the tank. It all goes in without a spill. I then switched on the ignition, waited 1 minute switched it off and started the van. No change. Still getting the adblue warning and 550 miles of range. I did a couple more ignition cycles and restarts and then took it out for a 5 mile run. Still no change.

In desperation I bought another bottle of adblue and used about 3 litres of that. Still no change.

Last thing I attempted was to remove the battery for 15 minutes and then reconnect. No change.

I'm at a total loss as what to do now. I'm guessing it's rubber ducked and I need to try the dealer?

 

[Paynewright]

I have a theory that as the tank gets empty the adblue dries / crystallises on the sensors. As such I’m keeping mine always topped up and not dropping below 3k miles.

This is based on the crud thats formed around the top of the bottle I use.

Hopefully a few days driving around with a full tank will make any crystals soluble again!

 

[dubber36]

A fella that I know had big problems with the Adblue on his Transit Custom based camper after he had it parked up for over a year. That had all crystallised and gummed everything up.

 

[Cuiken]

I'm hoping it's not got all gummed up. The van is our daily driver and I haven't knowingly allowed the adblue to go below 3000 miles range.

It does seem though that the sensor could have become stuck at 3000 miles and then fallen to 650 in one step somehow.

Hopefully @Paynewright is correct and a couple of days driving around properly full will free it up.

I fear this may become a faff to sort... Loving the added pressure of having a mileage countdown within which I need to figure it out

 

[Cuiken]

Here's an observation. Before I topped up the adblue, the van was asking for a specific amount (1.75 - 2.25 gallons).

While the mileage had not increased from 550, it's no longer asking for a specific quantity of adblue. Seems to suggest that is just got itself confused.

In this case, should I be still expect the mileage to reduce?

 

[teamfly]

Had this problem a couple of years back . Didn't recognise addblue being added but kept counting down miles to no start . Into dealer & I think was reset . Not certain as was in Netherlands so workshop printout in Dutch .
No issue with this since in 2 years / 20 k miles .

 

[Paynewright]

I wonder if disconnecting the battery will force a reset? I’ve seen it written, but never done it, about touching together the two disconnected battery connections to fully de-energise the electrical system??

I’d just try disconnecting the earth for 10 mins and see.

 

[Tourershine]

This happens on my T6 from time to time. In fact it did it yesterday on the way to a job in Cumbria.
I just ignore it now, because it resets itself after a few miles.

 

[dubber36]

I don't think that this has anything to do with this issue, but just to add to the thread, I leave the ignition on (not engine running) when filling the Adblue. I have the DIS showing the AB range, after filling, by the time I've walked round from the filler to the drivers door, the DIS will be showing 6000 miles.

Another thing I do is change the units in the DIS to metric. This gives the the amount to add in litres. Oddly, the amount it asks for in gallons doesn't always tally with the same setting in litres.

 

[Cuiken]

I wonder if disconnecting the battery will force a reset? I’ve seen it written, but never done it, about touching together the two disconnected battery connections to fully de-energise the electrical system??

I’d just try disconnecting the earth for 10 mins and see.

Good shout but that was one of the first things I tried. No joy.

 

[Cuiken]

Noticed this nothing that the actual message now reads 'Adblue Error' along with not asking for any specific quantity of to up. I can't recall if said that initially or if that only happened after I filled it.

Theoretically I could have overfilled it so I'll maybe try syphoning out 5L it so today and see if that changes anything.

 

[Cuiken]

Pulled 6 litres of Adblue out of the van with a vacuum syphon pump thing. Ignition on, waited 1 minute...... No difference. It's still reporting 'Adblue Error'.

So, booked it into the dealer next week.

I'm planning one last ditch attempt to fix it before then though.

Here's my plan. I know the tank was 'brimmed' with 13l of Adblue. This was after I added the initial 10l and then topped up with another 3l (after the 10l did not seem to work). Given it's a 13l tank, I probably over filled by adding 13l on top of what was already in there. With ~500miles of range left I'm guessing I had ~1L in there already and so had ~14L in total.

So, I just pulled 6L out (accurately measured). If I now put 4L back in I should be very nearly full.

At this point I can try a reset using VCDS and see if that fixes it (using method below).

If that doesn't do the trick then I probably have to conceded it's a dealer job.

 

[rod_vw]

Watching

 

[Cuiken]

I'll try not to keep you waiting

All this is just off the back of the comment from the dealer when I made my appt. He reckoned I'd overfilled and, best case, they'd need to drain the tank and reset. I think the step he was missing was, drain the tank, fill to actual capacity, reset sensor. Certainly the VCDS video reckons you need to reset with a full tank.

Being lucky enough to have a home VCDS kit I should (hopefully) be able to approximate this process myself.

Only anomaly is why it dropped from above to 1500miles of range to 650miles in one step. Possibly suggests the sensor is awry. I've seen this '650 miles' number show up on other threads as a precursor to 'then the dealer took all my money away'.

 

[mmi]

Being lucky enough to have a home VCDS kit

Before anything else please read engine's "Blockmap/Measuring Values" data and fault codes please.

VCDS -> Applications -> Controller Channel Map ->

Tick/fill boxes as above and hit Go.
VCDS flashes screens for a moment (when finished hit "Done, Go Back") and there will be file blockmap-01-... in folder C:\Ross-Tech\VCDS\Logs\....

 

[Cuiken]

Before anything else please read engine's "Blockmap/Measuring Values" data and fault codes please.

VCDS -> Applications -> Controller Channel Map ->

Tick/fill boxes as above and hit Go.
VCDS flashes screens for a moment (when finished hit "Done, Go Back") and there will be file blockmap-01-... in folder C:\Ross-Tech\VCDS\Logs\....

Too late I did a simple fault code read and found a couple of errors. The first was 'no reduction agent flow' (that'll be the adblue then) and the second was 'NOX reading implausible'. Both these faults were listed as intermittent. I got trigger happy and reset them. I did follow your advice afterwards but I'm guessing I'll have lost any useful info?

That said. I have managed to fix the issue! Though I don't know quite how.......

Here's everything I did from the begining.

1. Adblue Error came up on the dash on Sunday. Said 650 miles remaining, please add 1.25 <-> 2.25 Gallons of Adblue. This was a bit odd since I'd not had the 1500 mile or 1000 mile warnings and the range reported over 2000 miles the day before.

2. Got home with 600 miles remaining. Added ~10L of Adblue (2.2 Gallons). Waited 30 seconds, started the van. No change to Adblue level reading.

3. Drove about a bit normally (as some have recommended) until the Dash said 550 miles remaining. No change.

4. Added another 3L of Adblue. No change.

5. Syphoned out 6L of Adblue. No change.

6. Added 4L back in (to get to 'full'). No change.

7. Read and reset fault codes (as described above) and took it out for a 30 mile run in sport mode to ensure the whole system got up to temperature. No change.

8. Plugged the VCDS thing back in and reset the SCR level and the SCR learned behaviours (Basic Options menu in the Engine module, not the same place as the youtube video). I also tried reading back the Adblue level via VCDS before and after but it did not work (timed out). As an experiment I tried reading back some other values and they all timed out so I might be using the tool incorrectly. No change.

9. In desperation took the van out for another 30 mile drive. During this drive the Dash reported a drop from 550miles down to 500 miles and then (about 10 miles in) suddenly the whole system seemed to recover and it jumped up to 6500 miles of range. When I got home I re-read the fault codes and there were none.

So, what fixed it? I honestly have no idea. Potentially it was just the drive in sport mode (Adblue only works when the systme is hot enough so nothing will change on a short/cold journey) or maybe it was the syphoning out the tank.... or the SCR resets....Irritatingly, I just don't know. Maybe it'll go on the fritz again next week. We'll see.

Either way, it's fair to say the Adblue system seems to be fragile/fussy in the extreme. What a totally unnecessary palaver.....

 

[Cuiken]

Just had a thought (not that I'm obsessively trying to make sense of this).

What if the core issue was that my Adblue sensor was originally dramatically over measuring? This would make sense since the range dropped suddenly from ~2000 miles to 650 miles. It also makes sense since I managed to add more than 13L of Adblue into the tank without overflow (it was definitely pretty empty).

Additionally, this 650 miles range thing crops up pretty regularly in discussion of Adblue oddities on the T6 and California. Basically, others have reported their range dropping from a high value abruptly to 650 miles. Perhaps 650 miles is a magic number that indicates an actual issue with the Adblue system rather than a lack of Adblue. Ultimately, get yourself to a dealership. During my reading I found discussion that other VWs will default to 200 miles of range in similar situation.

So, what if I actually simply ran out of Adblue? That would make some sense since it is over 5000 miles since I last filled it. I was surprised by how slowly it was being used. It would also explain the two error messages (no reduction agent flow, NOX emissions high).

Taking a guess that I'm right about the abrupt change to the 650 mile number being a response to the error codes (specifically the 'no reduction agent flow' code), perhaps the van simply needed to sense 'reduction agent flow' in order to revisit the Adblue measurement. This hadn't happened after my first 10 litre 'fill' because either I had not got the cat up to a high enough temperature to prompt the use of Adblue or because I had needed to reset the error message first. The latter would make sense since the van won't want to update the mileage remaining if the Adblue system is judged to be broken. Instead it would want you to go to a dealership.

I look forward to revisiting all this next time it throws an Adblue wobbly.

 

[mmi]

. I did follow your advice afterwards but I'm guessing I'll have lost any useful info?

Well, not sure. There are quite a few event counters which still might have some data. Certainly interested to have a look. Also the actual VCDS fault code listing would be interesting.

I also tried reading back the Adblue level via VCDS before and after but it did not work

That's strange. Correct steps to read data would have been:
VCDS > Select Control Module > Engine > Adv. Meas. Values...

The "650 miles remaining" issue sounds similar an old software quirk - which, among quite a few others, was fixed by a software update in 2019-20.

 

[Bigsidavies]

The whole ad blue distance thing is crazy. Mine was showing that it wanted 1.5 gallons so I put 6 litres in and it only went to 3500 miles. I’ve done 1500 miles since and it’s just dropped to 3000 miles remaining. So the calculations make no sense. I was going to give it another top up but the minimum delivery at the pump is 5L
Glad yours is sorted and it gives the rest of us hope for the future.

 

[BaggieJim]

Not sure where you're at with this but I have 6 years of agony as a T6 owner from new, with this exact problem. It's been escalated to VW 'Customer Care' ''Executive Office'' (executives of what I am not quite sure) and my van is now in for the 8th or 9th time with the problem, under extended warranty, 1 year of which VW paid for in recognition of the fault.
I've had heater glow plugs replaced, Nox sensor replaced, adblue flow rate sensor replaced & recalibrated, and its still going on. VW are clueless and are covering us the issue. I'll write a summary when I have time, but in essence I will never buy a VW again due to their abysmal Customer 'Care' despite the overinflated reputation of their vehicles.
I was told their flow path ultimately is a recall to Germany, which they haven't followed and a VW dealership recently even asked if I considered selling the vehicle on? Incredible.

I'll be going public with all details to expose how bad this issue is and following a legal path to ensure VW own their responsibilities.