06/10/2025
3min

Simple and effective prevention of crystals in the SCR system

#Car

#Truck

#Vintage Cars

If diesel vehicles are equipped with an SCR system – i.e. with a system for selective catalytic reduction that reduces harmful nitrogen oxides using a urea solution (e.g. AdBlue®) – then a contribution to the environment has already been made. But there is a small, often overlooked vulnerability: Crystal formation in the SCR system. This is exactly where our DEF Anti Crystal Additive comes into play.

What’s the problem with crystals?

In practice, deposits and crystal formation occur in the AdBlue® tank, in lines or injectors on many vehicles – especially when driving short distances or in winter. This can have several unpleasant consequences:

Blocked nozzles in the SCR system
Error messages in the cockpit
Increased consumption or even system failure
In the worst case, a workshop visit with high repair costs

These crystals are formed by the natural aging of AdBlue® or by residues – especially if the vehicle has been idle for long periods or if the dosing is incorrect. This can lead to the formation of additional poorly soluble substances such as biuret, cyanuric acid or ammelide - these are deposited in the SCR catalytic converter and impair its function.

Even low-quality AdBlue® that does not comply with the ISO 22241 specification – for example with too many foreign substances such as magnesium, calcium or sodium due to unsuitable water – can lead to clogged injection nozzles and a faulty spray pattern, but above all to malfunctions and damage to the SCR catalytic converter. This, in turn, significantly reduces the efficiency of the emission control system.

The advantages of DEF Anti Crystal Additive at a glance

The additive was specially developed to prevent precisely these problems – proactively.

The advantages at a glance:

Minimizes the formation of urea crystals
Protects the entire AdBlue® system – from tank to injector
Optimizes the discharge behavior, e.g. of the return line
Reduces the formation of biuret and triuret (condensation product of urea)
Ideal for all SCR diesel cars and light commercial vehicles

Who stands to benefit from DEF Anti Crystal Additive Concentrate?

Using DEF Anti Crystal Additive Concentrate makes sense for people who have a diesel car with AdBlue and …

frequently drive short distances
leave their vehicle parked for longer periods of time
have had or want to avoid problems with crystal formation
are tired of visiting the workshop because of the SCR system

Conclusion: Low effort, high impact

With a small sip of high-tech chemicals, the SCR system can be protected, the risk of expensive repairs reduced and the service life of the exhaust gas aftertreatment system extended. Clean for the environment – and good for the car. Even with critical driving profiles (e.g. stop-and-go, short distances, city traffic), the additive ensures a stable spray pattern and reduces the risk of stubborn deposits forming.