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AdBlue: Explained

Updated: Mar 30, 2022

What is AdBlue? And Why Is It Important?

If you don’t drive a VW, Audi, Skoda or SEAT in diesel flavour, then the chances are you may not have heard of AdBlue. But what is AdBlue? What’s all this talk of a diesel engine-specific fluid. Which only came into being a few years back to slow down the speed at which oil-burning vehicles are killing our planet.

That might be an over-exaggeration, but you get our drift.

This environmentally-friendly liquid has been created to fully comply with emissions regulations. A subject matter which is fluid itself. But this doesn’t answer the basic question. As to how the magic happens.

Cue the next few paragraphs.

Which are hugely important if you own a diesel Volkswagen, Audi, Skoda or SEAT model. Typically found within the Volkswagen AG range. Focusing solely on any diesel vehicle that’s been built post-September 2015.

What Exactly is AdBlue Though, And Why Might I Need It In My Volkswagen Audi Group Vehicle?

Without getting bogged down in scientific formulas, AdBlue is a biodegradable solution. A completely harmless liquid, it was designed to help diesel vehicles meet the latest Euro exhaust emissions legislation

In terms of the breakdown of ingredients, we’re talking 32.5% urea. Together with 67.5% deionized water.

The latter being created by running either tap, spring or distilled water through an electrically charged resin. Usually a mixed ion exchange bed with both positive and negative charged resins are used. But that’s quite enough science.

Of course, when people ask what is AdBlue, we can confidently say that one thing it’s not. That thing being pig’s urine. As urban legend and soothsayers would have you believe.

AdBlue is made from synthetic materials and takes the form of a colourless liquid. It’s less a fuel additive, more a method of limiting emissions produced by diesel cars

In its most rudimentary terms, AdBlue is the most commonly used diesel exhaust fluid. Or DEF for short. It’s a trade name registered by the German car manufacturers association. Which means not all vehicles use it as such. Volkswagen’s and Audi’s certainly so though. 

But Just How Does It Work to Safeguard Both Our Health and That Of Planet Earth?


Simple that is, if you studied science to an advanced level. Otherwise it’ll need a little explaining. 

Let’s rewind.

Modern day diesel engines utilise a treatment system which essentially blends the AdBlue with a vehicle engine’s exhaust gasses. This is called selective catalytic reduction.

Abbreviated to the more easily remembered acronym of SCR. All this alchemy leads to a chemical reaction which converts nitrogen oxides (NOx) into nitrogen, water and carbon dioxide (CO2).

The resultant gasses emitted negate to threaten either the environment or our wellbeing. 

How Do I Know If My Vehicle Has an SCR System?

In order to comply with Euro 6 regulations regarding emissions which were introduced back in 2014, all diesel powered vehicles were equipped with SCR systems.

Which means – hypothetically at least – that all diesels built post-2014 should utilise AdBlue

What If I Choose To Not Use/Ignore My Vehicle Manufacturer’s AdBlue Warnings?

Unfortunately SCR-equipped vehicles tend to compromise the performance of a diesel engine.

In the event that AdBlue levels fall short of manufacturer requirements, then one possible upshot is that owners risk their vehicles failing to start. However, the driver does receive plenty of notification before this becomes an issue.

Thanks to low-level warning lights appearing on the dashboard. And a long time before the AdBlue reservoir becomes perilously depleted. 

Where Can I Acquire AdBlue? Is It Easily Source-able?

In lots of places, and yes.

AdBlue has become more omnipresent in the past few years, with a host of locations now ensuring that it’s readily available. These include vehicle dealerships, supermarkets, online and on countless fuel-providing forecourts up and down the UK.

In similar ratios to electric charging points being increasingly more widespread. 

How Often Should AdBlue Levels Be Topped-up?

This is the million dollar question.

Well, sort of. And based largely on consumption.

And it all hinges on a number of variables which alter from individual to individual.

Driving style is one example. While the length and types of journeys the vehicle is used for are other key elements which should be taken into consideration. 

The ballpark figures can be fairly vague. Anywhere from 3,000 to 12,000 miles between AdBlue refills. Which means it’s not uncommon to have to refill tanks on average between primary service intervals

The bottom line is your vehicle will make you aware of just when you need to top-up the AdBlue tank with a dashboard-mounted warning light that will illuminate as a means of forewarning. And similar to a digital petrol gauge, will countdown/remind the driver of just how many more miles they have. Before needing to replenish their AdBlue reservoir.

Get In Touch With WCC Neston If You Experience Any AdBlue Problems

Hopefully now that we’ve answered the ‘what is AdBlue‘ question, we need to explain why customers might bring their vehicles to us with AdBlue problems? 

By and large customers approach WCC Neston to book their diesel vehicles in for system resets.

Specifically if the countdown to AdBlue tank topping-up has elapsed. And the vehicle has effectively shut down. Rendering the car immobile.

Our team of technicians will perform AdBlue system repairs, which include a full software update on the vehicle which has experienced the issue.  

These specialist rectifications will thereafter ensure that the vehicle is once more driveable.

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