Ad closing in a few seconds...

Citroen Grand C4 Picasso - Feeling a little AdBlue

  • Diesel detergent requires replenishing; threatens not to start
  • Refilling could be easier but only required every 12,500 miles
  • Picasso’s thirst for diesel continues to gently dwindle too

I could really do with the services of Jennifer Aniston right now. Purely in a professional capacity, naturally. Let me explain.

A couple of weeks ago I pressed the Citroen Grand C4 Picasso’s starter button as normal one morning and, in addition to the usual cold-start clatter quickly settling into a sedate thrum, there was a high-pitched series of beeps accompanied by a message on the upper dashboard screen.

“Refill emissions additive: Starting prevented in 1500 mi” it read, with the word “urea” appearing twice in close proximity.

What’s an emissions additive, will it really prevent the car from starting and, more disconcertingly, urea sounds like it might somehow be related to urine, doesn’t it?

AdBlue explained

This is the point you’ll just have to imagine Jennifer has cheekily interjected with “now for the science bit.”

Chances are when you’ve stopped to buy fuel recently you’ll have also seen large bottles of a liquid labelled AdBlue – this is the aforementioned fuel additive and it’s required for diesel cars to pass the latest Euro 6 emissions regulations.

Essentially it’s a detergent created to reduce Nitrous Oxide (NOx) emissions from diesels’ exhausts. Because it can’t be pre-mixed with the diesel it requires replenishing every so often – in our long-term Citroen’s case, every 12,500 miles or thereabouts.

Choose to ignore the warnings and the ever-dwindling mileage countdown and yes, your car won’t start, because without the AdBlue it’s impossible to meet the low emissions levels.

And urea? The substance itself is 32.5 percent of the AdBlue recipe, the remainder being deionised water. It’s an organic compound occurring naturally in mammals to excrete nitrogen from the body via urine. So I wasn’t taking the pee after all.

Refilling the AdBlue tank

If you find refilling your car with petrol or diesel a chore, chances are you’ll pop to your local dealer to get them to replenish the AdBlue, but I did it myself to prove even the car maintenance-inept can manage it.

It should also be replenished as part of your car’s service schedule too, although as they’re every 20,000 miles or 12 months for our Picasso, I was ahead of the game.

If you’re driving a modern diesel you may well have spotted your car needs AdBlue because there’s a second filler neck behind the fuel flap. Not so with the Grand C4 Picasso – its 17-litre tank is accessed, less conveniently, under the right-hand side third row seat.

On the Citroen there are two caps to remove to access the tank – a larger black one with a smaller pale blue one underneath covering the neck of the filler. Before you refill it it's essential you double check the AdBlue meets the quality standard ISO 22241.

Due to the AdBlue I’d bought coming in 10-litre bottles, and the fact the filler neck’s below the height of boot floor, you’ll need something along the lines of the long funnel in the pictures, otherwise you’re liable to splash it inside the cabin. Despite the name AdBlue is colourless and doesn’t irritate the skin particularly but it’s always best to clean up any spillages as quickly as possible.

Once full, it’s simply a case of securing both of the caps and re-starting the car – which satisfyingly it does with no mention of urea or threats to prevent it from working. An easy job and in reality only a little more awkward than using a diesel pump.

Economy update

That’s a diesel pump I’m finding I’m visiting less frequently too, thanks to the Citroen’s ever-decreasing thirst for diesel. Typically with each tankful, which lasts for around 500 miles a time, the average consumption improves by 0.1mpg, meaning that now it’s up to 42.3mpg.

While it’s improving it’s still some way short of the official combined average of 61.4mpg, that’s never going to be achievable in real world conditions.

So far the best single-tank figure achieved was 54.5mpg by fellow Parkers writer Adam. Presumably his bones are made of polystyrene and his trainers filled with helium for such a deftly-light throttle application.

Total mileage: 13,076 miles (started at 394)

Average mpg: 42.3mpg