AdBlue is the urea solution used in the SCR (Selective Catalytic Reduction) system of diesel vehicles to reduce NOx emissions. AdBlue Off refers to adjusting the software functions of this system and is intended only for uses permitted by regulations.
What are AdBlue and SCR?
AdBlue is a colourless solution of about 32.5 percent pure urea by mass mixed with water. When sprayed onto the SCR catalyst in the exhaust line, it converts harmful nitrogen oxides (NOx) into nitrogen and water. It became widespread on diesel vehicles with the Euro 6 standard.
Components of the SCR system
- AdBlue tank with level and temperature sensor
- Supply and dosing pump module
- Injector (dosing valve) that sprays the solution into the exhaust line
- SCR catalyst
- NOx sensors before and after the exhaust
- Heaters that warm the tank and lines in the cold
AdBlue in cold weather
AdBlue freezes at around -11 °C. For this reason the systems include elements that heat the tank and lines. In cold climates, heater or sensor faults are a common cause of warnings. Frozen solution is not damaged and can be used again once thawed, but you need to make sure the heater works.
Common mistakes when using AdBlue
- Using a solution that does not meet the ISO 22241 standard or is diluted
- Filling water or another liquid instead of AdBlue (this damages the system)
- Pouring AdBlue into the diesel tank or the other way round
- Using old solution left for a long time outdoors and in the heat
- Ignoring the low-level warning
Common problems in the AdBlue system
- AdBlue level or quality sensor faults
- Dosing pump and injector blockages
- Solution freezing in the cold and heater faults
- NOx sensors sending faulty values
- The engine-start lock function with a low-level warning
Why can it be costly?
SCR components (dosing module, NOx sensors, catalyst) are expensive and faults can recur. That is why vehicle owners and workshops may consider adjusting the system on the software side.
What does AdBlue Off software do?
Monitoring, dosing and warning functions of the SCR system are adjusted in the ECU, which manages the fault codes produced by the system and the related restrictions. The condition of the physical components does not change with software.
What to check first
- AdBlue quality and level
- Sensor connections and wiring
- Cleanliness of the dosing injector
- Correct reading of the fault codes
How to create an AdBlue request at MyEcuFile
- In the panel, select the vehicle and upload the original ECU file
- Tick the AdBlue/SCR option (on its own or together with DPF and EGR)
- In the request note, state the fault codes and any hardware changes made
- Download the file from the panel and keep a backup of the original file
Modifications to emission control systems are prohibited on road vehicles in many countries. Such work is intended only for racing/track use or where the relevant regulations allow it. Compliance with the regulations of the country where the vehicle is located is the responsibility of the workshop placing the request.
Frequently asked questions
In many vehicles an engine-start lock engages when the level gets very low and the vehicle cannot be restarted. It is therefore important to keep track of the level.
No. Sensor, wiring or quality problems can give the same warning. The fault codes need to be read correctly.
It is prohibited in many countries on public roads. It should be considered only for permitted uses.
Consumption varies with the vehicle and driving conditions; it is usually a few percent of fuel consumption. The vehicle's manual gives the correct value.
No. Water or non-standard liquids damage the dosing system and the SCR catalyst and do not perform the function.