Understanding AdBlue: A Guide to Its Purpose and Necessity for Diesel Cars

In the quest for cleaner and more environmentally friendly transportation, AdBlue has emerged as a critical component in modern diesel vehicles. This fluid plays a significant role in reducing harmful emissions, particularly nitrogen oxides (NOx), which are a major contributor to air pollution and in turn, health issues. In this article, we’ll explain what AdBlue is, its composition, working mechanism, usage, and the necessity of adhering to its maintenance requirements to ensure optimal engine performance and emissions control.

What is AdBlue and How Does it Work?

Selective catalytic reduction (SCR) is the name for the science behind what makes AdBlue work. AdBlue also known as Diesel Exhaust Fluid (DEF)is a clear, non-toxic, and non-flammable fluid composed mainly of demineralized water (approximately 67.5%) and urea (approximately 32.5%). It’s used in selective catalytic reduction (SCR) systems in diesel engines to help reduce harmful nitrogen oxide emissions. The SCR process involves injecting AdBlue into the exhaust system, where it reacts with nitrogen oxides to convert them into harmless nitrogen and water vapor.

The SCR process starts with the injection of AdBlue into the exhaust system, which releases ammonia. When the exhaust gases pass through the SCR catalyst, the ammonia reacts with the nitrogen oxides in the presence of oxygen, converting them into nitrogen and water. This chemical reaction is essential for reducing NOx emissions, making diesel engines more environmentally friendly.

The environmental benefits of using AdBlue are substantial, as it helps vehicles meet strict emissions regulations. The reduction in NOx emissions lead to cleaner air and improved air quality, which is crucial for protecting human health and the environment. Additionally, lower NOx levels contribute to the reduction of acid rain and the formation of ground-level ozone, both of which have adverse effects on the ecosystem.

Many countries and regions have set stringent emission standards to improve air quality, and AdBlue is a key technology that aids diesel vehicles in meeting these requirements. Compliance with these regulations is essential not only to avoid penalties, but also to be part of the collective effort to combat climate change and its associated impacts.

AdBlue Usage and Consumption Rate

The consumption of AdBlue varies depending on the vehicle’s make, model, and driving conditions. Generally, the AdBlue tank’s capacity is designed to last for several thousand miles before requiring a refill. The average consumption rate ranges from 2% to 6% of diesel fuel consumption, but this can vary.

To store AdBlue, many modern diesel vehicles are equipped with a dedicated AdBlue tank, which is separate from the fuel tank. The separate tank allows for easier monitoring and management of AdBlue levels. It’s important to maintain an adequate AdBlue level to ensure that the vehicle complies with emissions standards, as some countries and regions have strict requirements for diesel engines.

Monitoring the AdBlue level is important to ensure compliance with emission standards. To help drivers keep track of their AdBlue levels, many modern vehicles are equipped with onboard systems that monitor the levels and provide alerts when a refill is recommended. It’s essential to pay attention to these alerts and refill the AdBlue tanks promptly to avoid any potential issues with emissions compliance.

Running out of AdBlue can lead to an increase in NOx emissions, potentially resulting in a vehicle failing emissions tests or violating regulations. In some cases, a vehicle may even enter a ”limp mode”, where engine power is restricted until the AdBlue tank is refilled. To prevent such situations, it’s essential to pay attention to these alerts and refill the AdBlue tanks promptly to avoid any potential issues with emissions compliance.

Does My Car Require AdBlue?

Determining whether or not your car requires AdBlue is relatively straightforward. First, check your vehicle’s specifications or refer to the owner’s manual. The manual will provide clear information about whether your vehicle is equipped with an SCR system that requires AdBlue. AdBlue is primarily used in diesel engines, so petrol fuelled engines don’t typically require it.

It’s crucial to adhere to the manufacturer’s recommendations regarding AdBlue usage to ensure optimal engine performance and emissions control. Neglecting to use AdBlue when required can lead to increased NOx emissions, which not only harm the environment, but may also result in fines or restrictions in areas with strict emissions regulations.

Addressing common misconceptions or myths about AdBlue usage, some drivers may worry that AdBlue can negatively affect their vehicle’s performance or fuel efficiency. However, AdBlue is an essential component of the SCR system, designed to improve emissions control without compromising engine performance when used as directed.

AdBlue Handling and Refilling

Handling AdBlue safely is important to prevent any adverse effects on both the vehicle and the environment. AdBlue is a non-toxic fluid, but it shouldn’t come into contact with your skin or eyes. In case of contact, you would need to rinse with plenty of water. It’s also important to avoid spilling AdBlue on the vehicle’s exterior or surrounding surfaces, as it may cause damage to the finish.

As for refilling your AdBlue tank, many fuelling stations offer AdBlue dispensers, making it convenient for drivers to refill their tanks. These dispensers are typically located adjacent to the diesel fuel pumps, ensuring easy access for diesel vehicle drivers.

Alternatively, AdBlue refill kits are available, allowing vehicle owners to refill their AdBlue tanks at home. These kits often come with the necessary equipment and instructions for safely and effectively refilling the AdBlue tank at home. Hower, it’s crucial to ensure that you use the correct grade of AdBlue, as using an incorrect or contaminated product can lead to SCR system malfunctions.

The cost of AdBlue is relatively reasonable, and its availability has significantly increased as more diesel vehicles adopt SCR technology. For most drivers, the expense of AdBlue is minimal compared to the environmental benefits it provides and the potential consequences of non-compliance with emissions regulations.

Ignoring AdBlue maintenance can have several negative consequences. As mentioned earlier, running out of AdBlue can lead to increased NOx emissions resulting in a vehicle failing emissions tests or violating regulations. Additionally malfunctioning of the SCP system due to incorrect or contaminated AdBlue can lead to expensive repairs and decreased fuel efficiency.


AdBlue is an indispensable tool in the fight against air pollution and climate change, especially in diesel vehicles. By understanding its purpose, working mechanism, usage, and the importance of proper maintenance, vehicle owners can ensure that their diesel engines run efficiently, meet emissions standards, and contribute to a cleaner and healthier environment. Adhering to the manufacturer recommendations and being responsible in handling and refilling the AdBlue tank will playa crucial role in making diesel vehicles more eco-friendly and sustainable. As we continue to prioritize environmental sustainability, embracing technologies like AdBlue is a big step in the right direction for a greener future.

Where to Go for More Information

For any advice or recommendations about anything having to do with your vehicle, check with the experts here at Used Car Sales Direct. We have been one of the most trusted used car dealers in this area for years, and we have a vast wealth of experience offering quality vehicles. If you need to replace your car, we have a huge inventory of low mileage cars to choose from.Each of our used vehicles has gone through a multi-point analysis performed by one of our highly trained technicians. They meticulously check the vehicle inside and out, under the bonnet, and on the road to make sure that the vehicle you purchase here is in tip top shape. Whether you’re in the market for one of our vehicles, need service or repairs to your vehicle, or need to get an MOT inspection, we are the place to go.

If you’d like to learn more about our services, visit our website or give us a call at either of our locations. In Exeter, call 01392 717888, and in Wellington call 01823 0795 437. Better yet, stop by and see us! We look forward to serving you!