The mysteries of AD Blue.

Pips Dad · Jan 18, 2019

Is it me or or has anyone else been unsure of adding AD Blue?
Well my 5 month old Cali started to tell me that it was starting to get a bit low and would need topping up soon as the MFD was starting to count down from 1200 miles. As it is the first vehicle I have owned that used this stuff, I read the manual and after reading the pages of info on the subject it didn’t seem obvious to me at what point to refill the tank.
I had bought a 10 litre bottle from Tesco for £11.00 in rediness but wondered if I needed to wait until the display was showing nearly empty or, say, 100 miles to go.
Well, I decided to top the tank up (1000miles to go on MFD) and the display now shows 4000 miles before I need to think about another top up.
So if anyone is in any doubt as I was, just top the tank up as you would top up diesel.
In other words, don’t let it run empty as the engine will not run! ( according to the handbook)

Alan Andrews · Jan 18, 2019

And as has been written many times....never overfill the Adblue tank as this can do some serious damage.

Pips Dad · Jan 18, 2019

Alan Andrews said:
And as has been written many times....never overfill the Adblue tank as this can do some serious damage.

Alan, I filled it up using the flexible spout that came with the AD Blue until it was full. When you say don’t overfill I assume you mean don’t let it flood down the paintwork as it can damage the finish if left on?
I filled it to the top as the VW service dept told me to do that. The vehicle runs well after filling up.

Volkywagen · Jan 18, 2019

I fill mine to the brim with local pump. Done it 5 times now from new and it’s been fine.

Ting Tong · Jan 18, 2019

Pips Dad said:
Alan, I filled it up using the flexible spout that came with the AD Blue until it was full. When you say don’t overfill I assume you mean don’t let it flood down the paintwork as it can damage the finish if left on?
I filled it to the top as the VW service dept told me to do that. The vehicle runs well after filling up.

No don’t brim the tank. The issue is it covers the ultrasonic sensor and can cause it to think the tank is empty which shuts the engine down and involves a tow to the dealer for a chargeable fix. Put in exactly the amount it asks for or less.

B J G · Jan 18, 2019

There has been a warning on here on other threads NOT to brim fill the Adblue tank as it is said to cause emission system problems (deemed to be driver fault by VW).
VW failed to design a tank that can be filled to the pump nozzle cutout point apparently.
Only fill as much as is displayed on MFD info. which isn't very user friendly as it gives the fill max in gallons if you have it set to miles for mpg and range information.
I intend to query my dealer next week when in for a service.

I've never figured out why we have metric money and weights plus fuel sold by the litre but distances and speeds are still in imperial miles.