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What is AdBlue and does my car need it?

22nd May 2024

Most diesel vehicles manufactured after 2015 require AdBlue to comply with the current emissions standards in the UK (also known as Euro 6). AdBlue helps to remove harmful substances from the exhaust. AdBlue is also known as diesel exhaust fluid and is a colourless and non-toxic solution that needs to be added to your vehicle when the dashboard light indicates that it is running low.  

If you plan to upgrade or buy a new diesel-powered vehicle, you may wonder if your car needs it. Merityre’s guide covers what you need to know about AdBlue. 

What is AdBlue made of? 

AdBlue is made from a mixture of ionised water and urea. Typically, the exhaust fluid consists of 32.5% urea and 67.5% ionised water. While it is possible to obtain urea and distilled water to make AdBlue yourself, it’s not recommended as the urea needs to be high-purity and requires a specialist process to produce it. It is recommended to buy AdBlue from a local garage or petrol station. Using homemade AdBlue can damage the SCR system and the engine, thus causing your diesel vehicle to fail the emissions test.  

How does AdBlue work? 

AdBlue works alongside the selective catalytic reduction system to reduce nitrogen oxide (NOx) exhaust emissions. The AdBlue is injected into your car’s exhaust system, mixing with the exhaust gases to turn nitrogen oxide into water vapour, nitrogen, and carbon dioxide (CO2). This reduces harmful emissions being released from the exhaust tailpipe into the atmosphere. 

Does every diesel vehicle need AdBlue? 

No. AdBlue should be used in diesel vehicles fitted with a selective catalytic reduction system. You can find out whether your van or car uses an SCR from the owner’s handbook.  

Why should I not put AdBlue in a diesel fuel tank? 

Accidentally pouring AdBlue into your car’s diesel fuel tank can cause significant damage to your engine. If you have mistakenly added AdBlue to the fuel tank, turn the engine off immediately, drain the fuel from the tank and replace the fuel filter. After you’ve done this, flush the fuel system with new diesel, ensuring any remaining AdBlue is removed from the tank. Once the AdBlue is removed, we recommend booking your diesel car for a service. One of our Merityre specialists will ensure there is no damage caused by the AdBlue solution. 

What happens if I don’t use AdBlue? 

If your SCR-equipped diesel car runs out of AdBlue, you will be unable to restart the engine, once the car has stopped as the ignition will not work. Your car’s dashboard will warn you when running low on the fluid. As the level of AdBlue drops, the engine performance will be affected and as the level becomes critical, you will not be able to exceed 30mph until the levels have been topped up again.  

Can I fill my petrol car with AdBlue?  

No, putting AdBlue in a petrol-powered vehicle could lead to expensive repair costs. Vehicles fuelled by petrol do not require AdBlue and if it is used, it will clog the fuel system and damage the engine. 

However, if you accidentally put AdBlue into the petrol tank, it’s essential to address the issue promptly. Do not start the engine as the contaminated petrol needs to be removed, alongside cleaning and flushing the fuel system components, such as the injectors and the fuel filter. 

Have you noticed that your diesel-powered vehicle’s fuel filter is struggling to filter out contaminants? It’s time to get your diesel filter replaced. With our gold service, we can replace the fuel filter on your vehicle for you. Book a service at your nearest Merityre branch across South East England today.