What is AdBlue?
In this article, we will comprehensively and professionally examine:
What is AdBlue and what is it made of?
The role of AdBlue in diesel vehicles
How it works in the SCR system
How to use, maintain, and purchase AdBlue
AdBlue is stored in a separate tank and is never mixed with fuel. This fluid is part of the Selective Catalytic Reduction (SCR) system, which we will discuss in detail later.
As mentioned, AdBlue is a combination of industrial urea and ultra-pure water. The urea used must be of high purity to avoid causing any disruptions in the sensitive vehicle systems. This combination is obtained through a specific process and is produced according to ISO 22241 standard.
The main use of AdBlue is to reduce emissions from diesel vehicle exhaust gases, especially the toxic gas nitrogen oxide (NOx), which is a primary contributor to air pollution. This fluid is injected into new systems called SCR (Selective Catalytic Reduction), causing NOx to break down into nitrogen and water vapor—substances that are completely harmless.
SCR (Selective Catalytic Reduction) is an emission control system that converts NOx gases into harmless nitrogen (N₂) and water vapor (H₂O). This process is achieved with the help of AdBlue injection into the exhaust.
How it Works:
AdBlue is injected into the exhaust path before the catalyst.
At high temperatures, AdBlue decomposes into ammonia (NH₃).
Ammonia reacts with nitrogen oxides, converting them into nitrogen and water vapor.
If diesel vehicles don’t use AdBlue, they will not only produce more pollution but might also be prohibited from driving in certain cities or countries in Europe, and even domestically. Furthermore, if AdBlue levels are low or depleted, many vehicles will automatically shut down or have their performance limited.
AdBlue is a key factor in reducing the harmful environmental effects of diesel vehicles. Correct use of this fluid plays a significant role in decreasing greenhouse gases and air pollution. It helps vehicles comply with environmental standards like Euro 5 and Euro 6.
The amount of AdBlue consumed depends on the vehicle type, driving conditions, engine model, and its displacement. However, on average:
Diesel Passenger Cars: 1 to 1.5 liters per 1,000 kilometers
Medium and Heavy-Duty Vehicles: 3 to 6 liters per 1,000 kilometers
In modern vehicles, the remaining AdBlue level can be seen via a digital display or a warning on the dashboard.
Is AdBlue Replaceable?
No! Using fake or diluted substitutes will not only damage the SCR system but may also void your vehicle’s warranty. You should never use water or similar substances in place of AdBlue.
Storage and Preservation of AdBlue
Store in a dry and cool place.
Keep away from direct sunlight.
Maintain a temperature between -11 to +30 degrees Celsius.
AdBlue typically has an expiration date of 12 to 18 months.
How to Use AdBlue in Your Vehicle
AdBlue is poured into a separate tank in the vehicle and should never be mistaken for the fuel tank. Typically, a separate cap for AdBlue is provided next to the fuel cap or under the trunk lid. Filling the AdBlue tank must be done carefully to prevent contaminants from entering the fluid.
Here are the common indicators that your vehicle’s AdBlue level is low or empty:
“Refill AdBlue” warning on the dashboard
Yellow engine or exhaust light illuminated
Error message indicating reduced exhaust system performance
Vehicle not starting or operating in a restricted mode
How to Use AdBlue
AdBlue is stored in a separate, dedicated tank in the vehicle. In passenger cars, this tank is typically located:
Next to the fuel tank
In the trunk
Or under the hood, with a separate filler cap
Important Tips When Filling AdBlue:
Use only genuine AdBlue that carries the ISO 22241 standard mark.
Never mix it with fuel.
Prevent the nozzle from getting contaminated; introducing impurities will damage the entire system.
Once the bottle is opened, use it within less than one month.
AdBlue Price and How to Purchase It
The price of AdBlue varies in Iran and globally, depending on the brand, quality, volume, and point of sale. AdBlue is typically offered in packages of:
10 liters
20 liters
Barrels (for fleets and trucks)
For purchasing AdBlue, it’s recommended to buy only from reputable automotive parts stores or official dealerships.
Is AdBlue mandatory for all diesel vehicles?
What happens if AdBlue runs out?
Does AdBlue consumption affect engine performance?
Can AdBlue be produced at home?
What happens if AdBlue runs out?
Does the use of AdBlue increase fuel consumption?
Is AdBlue toxic?
