If you drive a diesel car, you need to know about AdBlue.

Not only does it play an important role in keeping your exhaust emissions under control, but your car won't go anywhere without it.

Read on and find out the 20 (or more!) things you need to know about AdBlue in 2024.


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What Is AdBlue?

AdBlue is the most commonly used Diesel Exhaust Fluid (DEF).

It is a trade name registered by the German car manufacturers association, so not every car uses it.

AdBlue is a colourless liquid stored in a separate tank, usually next to your diesel tank.

It is not a fuel additive but a method of limiting the emissions produced by diesel cars.


The AdBlue tank in a car.

The AdBlue filler cap is usually beside the diesel filler cap in your car.


What Does AdBlue Do?

AdBlue reduces the levels of harmful exhaust emissions in diesel cars.

It became compulsory for all diesel vehicles to use a form of DEF in September 2015 when the EU introduced Euro 6, their strictest emissions standard yet.

It works alongside the Diesel Particulate Filter (DPF) to reduce the amount of Carbon Dioxide (CO2) and Nitrous Oxides (NOx) released into the atmosphere.

Your car needs AdBlue as much as it needs fuel - it won't run without it!


What's in AdBlue?

AdBlue contains 2 parts deionised water and 1 part concentrated automotive urea.

Automotive urea contains Ammonia and Carbon Dioxide.

AdBlue is not made of pig urine or pure urine.

This is a complete myth.


Where Did the Myth Come From?

No one is quite sure where the urine myth originated from, but the confusion is down to the primary ingredient, urea.

Urea is a compound that breaks down nitrogen oxides into nitrogen and water, and it’s also found in urine.

The urea in AdBlue is manmade.


Is AdBlue Toxic?

AdBlue is non-toxic.

It is perfectly safe when used in the right conditions.

However, it is still a special mixture created for chemical reactions within your exhaust system, so it should not be used for anything else.

In addition, water is the primary ingredient, so it may be corrosive to certain metals.


Is All AdBlue the Same?

There are several different types of AdBlue.

These are differentiated by International Organisation for Standardisation (ISO) 22241 numbers.

ISOs ensure that the AdBlue you use is effective and has been created to the proper specifications.

Modern diesel cars run on ISO-22241-1, ISO-22241-2, or ISO-22241-3.

If you are unsure which type your car uses, consult your vehicle handbook.


How Does AdBlue Reduce Exhaust Emissions?

Your vehicle carefully injects AdBlue into the exhaust gases produced by your engine.

The ammonia in the urea breaks down the NOx emissions through a series of chemical reactions.

This means your exhaust releases Nitrogen and water vapour into the atmosphere instead of any harmful emissions.

As a result, AdBlue and other DEFs can reduce NOx emissions by up to 90%.


Does AdBlue Affect Fuel Consumption?

There is no evidence that AdBlue negatively affects fuel consumption.

It focuses on reducing exhaust emissions, so it doesn't mix with diesel at all.

Some vehicles' fuel consumption does benefit from using it (because it optimises combustion) but this is already integrated into manufacturers' figures.


Which Cars Use AdBlue?

AdBlue is not fitted to every diesel car. As it is a registered trademark, not every manufacturer is authorised to use it.

The cars in the following tables all use AdBlue.



A4 Avant A4 Saloon A5 Sportback
A6 Avant A7 Sportback A8
Q3 Q5 Q7



Series 5 Saloon Series 5 Touring Series 7 Saloon X5 X6



Berlingo Multispace C3 C4 Cactus





Land Rover

Discovery Discovery Sport Range Rover Evoque Range Rover Range Rover Sport



208 2008 308
30008 508 508SW
5008 Partner Tepee Traveller



Caddy California Caravelle Passat
Passat Alltrack Tiguan Toureg Transporter



C-Class Saloon CLS E-Class Saloon
Sprinter S-Class Saloon Vito


Does My Car Use AdBlue?

If your car is a diesel version of one of the models listed above, it is very likely to use AdBlue.

The information will be recorded in your vehicle handbook, so check there if you're not sure.

If your car is not one of the models listed above, it may use a different type of DEF or emissions-reducing technology.

Again, consult your vehicle handbook for more information.

Please note that petrol vehicles do not use AdBlue.


What Does the AdBlue Light Mean?

When your car starts to run low on AdBlue, you may see the following warning light (or something similar). 

The AdBlue light in your car may resemble a liquid being poured from a container. 


AdBlue warning light

Look out for this AdBlue warning light.


If you see the AdBlue warning light, this means you have about 1,500 miles of fluid left.

You should look to fill up your tank as soon as possible to avoid it running out.


How Do You Reset the AdBlue Light?

The best way to clear the AdBlue warning light is to refill your AdBlue tank.

Once the tank is full, turn the ignition on for about 30 seconds - without starting the engine - and make sure the warning light clears.

If the light doesn't clear, there may be an issue with the system.

This is commonly a fault with one of the sensors but it could be something else.

Each vehicle has a specific process to reset the AdBlue light.

Consult your vehicle handbook or search online forums to find out how to do so for your car.

If these don't bring you any answers - or the warning light persists - ask a professional mechanic for help.


What Happens if You Run Out of AdBlue?

Your car treats this DEF like fuel and won't run without it.

If your car runs out of AdBlue, it will enter 'limp home' mode.

Limp home mode limits your vehicle's power and performance, allowing you to get home or to a garage safely.

However, once you switch the engine off, it won't restart until you fill up your AdBlue tank.


How Much Does AdBlue Cost?

The cost of AdBlue can vary depending on which brand you choose and how you choose to fill it up.

On average, a 10-litre container costs between £10 and £15.

If you choose a public pump, you will pay per litre.

This price will vary from pump to pump.

If you book your top-up through BookMyGarage, it costs £20 for up to 10 litres.


Where Can I Find an AdBlue Pump Near Me?

Trucks and HGVs have used AdBlue since 2001, so there are plenty of public top-up points at motorway service stations.

However, some may not have been converted to work for cars, so check before you travel if you suspect your tank needs filling up.

Findadblue helps you find your closest AdBlue pump or retailer.

You can search by car brand or by their official partners and you just need to enter your postcode to see the entire list.


How Much AdBlue Do You Need?

You need between 10 and 11.5 litres to fill an AdBlue tank, on average.

Larger vehicles will need slightly more because their tanks are bigger.

However, you may need slightly less to completely top your tank up if you're refilling it just after the warning light came on.


How Long Does it Last?

A full tank of AdBlue lasts between 6,000 and 7,000 miles, on average.

1 litre of AdBlue lasts around 600 miles, but this can be affected by your driving style.

The more fuel your vehicle uses, the more AdBlue it will consume as well.

However, travelling 6,000 to 7,000 miles will empty your tank.

We recommend topping up every 5,000 miles to be safe.


How Do I Top AdBlue Up?

To top up your car's AdBlue levels, you will first need to located the AdBlue tank. 

This is usually next to the diesel tank, but can also be found under the bonnet. 

Check your vehicle handbook if you're struggling.

Using a funnel or anti-spill nozzle, slowly pour AdBlue from the container into your tank. 

Use as much as you need to completely fill the tank.

If your car needs a dashboard reset after a top-up, make sure you complete this as per the instructions in your vehicle handbook. 

Make sure your onboard computer has validated the refill before restarting the engine. 

This comes in the form of a dashboard message and may take a couple of minutes to come through. 


Can I Put AdBlue in the Diesel Tank?

AdBlue is not a fuel additive and it should never be added directly into the diesel tank.

If you suspect these have mixed together, do not start the car.

Call your recovery provider and get them to tow you to a garage where a mechanic can assess the damage.


What Happens if I Put Diesel in the AdBlue Tank?

Even the smallest amount of diesel can contaminate the entire AdBlue tank.

It can also cause serious damage to your exhaust system - which can be expensive to fix.

You might notice your car behaving oddly if you do start driving.

If your fuel level doesn't seem to have changed, your car feels strange or you see any warning lights after filling up, pull over as soon as possible and call your recovery provider.

If you accidentally put diesel in your AdBlue tank, the best thing to do is stay where you are and call your recovery provider.

To avoid expensive damage, do not start the engine.


What Is Selective Catalytic Reduction?

If your diesel vehicle uses AdBlue, then it will also use a treatment system called Selective Catalytic Reduction – otherwise known as SCR.

By mixing the AdBlue with the gases produced by your engine’s exhaust, the SCR can create a chemical reaction which makes these exhaust emissions less harmful.

As with DPFs, your vehicle will most likely use SCR if it was built after the introduction of the Euro 6 regulations.

You can check your vehicle’s handbook if you want to know for certain whether your vehicle uses SCR.

Selective Catalytic Reduction is a clever technology system, which can send DEF into the exhaust stream of your diesel engine, to trigger a chemical reaction which can turn nitrogen oxides into nitrogen, water, and carbon dioxide (CO2).

SCR is important because the use of AdBlue and similar DEFs can reduce the levels of these harmful NOx emissions by as much as 90%!

As Selective Catalytic Reduction relies on DEFs like AdBlue to function, it is incredibly important that you remember to top up your AdBlue levels when needed.

You can either do this yourself, or you can choose to have a professional garage perform this service for you.

Depending on how you use your vehicle, your AdBlue levels may need to be topped up more often, especially if you consistently drive at a higher speed.

Without AdBlue there to do its job, this could impact the air quality around you and cause potential respiratory problems.


Where Can You Buy AdBlue?

You can buy AdBlue at:

  • Some motorway service stations
  • Automotive suppliers
  • Local garages

Alternatively, you can enter your vehicle reg and postcode into our online booking tool to compare thousands of garages offering AdBlue top-ups near you and book your appointment in just a few clicks.

You can add it onto any MOT, service or other repair you need to make your life as easy as possible.


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How Will I Know When My AdBlue Tank Is Full?

What Happens When You Overfill the AdBlue Tank?

How Long Can I Drive After The AdBlue Warning Light Comes On?

How Much AdBlue Should I Add?