With the arrival of winter, owners of diesel cars equipped with AdBlue systems face an unexpected threat. As temperatures drop, the urea solution—normally ensuring eco-friendly engine operation—begins to crystallize inside the tank. This process occurs much faster and more intensely than during warmer months, potentially leading to serious malfunctions and costly repairs.
Mechanics note that many drivers mistakenly believe that simply topping up AdBlue regularly is enough. However, in winter conditions, this isn’t sufficient. Urea crystals can clog not only the tank itself but also injectors, pumps, and even damage the catalytic converter. As a result, the vehicle may switch to limp mode, lose power, or fail to start altogether.
Winter risks
In freezing temperatures, AdBlue becomes a real headache for owners of modern diesel vehicles. The crystallization of the solution leads to dense deposits that are difficult to remove without specialist intervention. If timely action isn’t taken, the SCR system (selective catalytic reduction) can fail, and repairs may become extremely expensive.
Cars operated in regions with frequent frosts are especially vulnerable. Even if a car spends the night in a garage, driving on cold roads increases the risk of crystal formation. In some cases, just one night at subzero temperatures is enough for solid deposits to appear in the tank.
Expert recommendations
Renowned auto mechanic Juan José Ebenezer, popular on Spanish-speaking social media, advises that you shouldn’t limit yourself to standard AdBlue maintenance. According to him, to prevent crystallization, it’s important to use special anti-crystallizing additives. These additives not only prevent crystals from forming but can also dissolve existing deposits.
Ebenezer recommends looking at products that can be added directly to the AdBlue tank. Among them are UreNox and the BNZ 21 anti-crystallizer, which he claims protect the system effectively even in severe cold. The mechanic demonstrates how BNZ 21 can literally dissolve urea crystals in seconds, breaking them down into fine particles that eventually disappear completely.
What to do if crystallization occurs
If crystals have already formed in the tank, experts advise resolving the issue promptly. In some cases, two doses of anti-crystallizer are enough to clean the system. However, if the pores and channels are completely clogged, even the most effective products may not help—in that case, the entire system will need to be disassembled and flushed.
Experts stress that prevention is always cheaper than repairs. Regular use of special additives during the winter months can help you avoid unpleasant surprises and keep your vehicle running smoothly. It’s especially important not to wait for the first signs of trouble—such as reduced power, dashboard warnings, or hard engine starts.
How AdBlue Works
AdBlue is a special solution used in diesel vehicles to reduce harmful emissions. It’s stored in a separate tank with a capacity of 10 to 15 liters and is consumed at a rate of about one liter per thousand kilometers. When the level gets low, the system warns the driver, but it does not immediately shut down the engine.
Not all diesel engines are equipped with the AdBlue system. It is only mandatory for vehicles that meet the Euro 6 emissions standards and above. Older models operate without this solution, and some modern engines are able to comply with emissions regulations without additional additives.
If AdBlue runs out or crystallizes, the vehicle may switch to emergency mode. In this case, power decreases, performance suffers, and if the system is completely blocked, the engine may not start at all. Additionally, crystals can damage expensive exhaust aftertreatment components.
If you didn’t know, Juan José Ebenezer is one of the most renowned auto mechanics in Spain, famous for his advice on TikTok and other social networks. His recommendations for diesel car maintenance are widely followed by drivers across the country. In his own workshop, he tests various additives and shares the results with his subscribers, helping them avoid common mistakes in the operation of modern vehicles.
