Can Automotive Urea Be Diluted with Water?
3 Answers
Automotive urea cannot be diluted with water. Automotive urea has high purity requirements and must not be mixed with water. Diluted automotive urea is substandard and may cause vehicle damage if used. Below is a detailed introduction to automotive urea: Overview: The SCR solution has significant advantages in the National IV diesel vehicle exhaust emission treatment system, and automotive urea is an essential additive for the SCR solution. With the gradual implementation of the National IV emission standards for diesel vehicles in various cities, the demand for automotive urea may surge. Others: The SCR system includes a urea tank (loaded with diesel exhaust fluid) and an SCR catalytic reaction tank. The operation process of the SCR system is that when nitrogen oxides are detected in the exhaust pipe, the urea tank automatically sprays diesel exhaust fluid, which reacts with nitrogen oxides in the SCR catalytic reaction tank through redox reactions, producing harmless nitrogen and water vapor for emission.
I've been driving heavy trucks for ten years and have seen many fellow drivers try to save money by diluting urea with tap water. Within two months, the engine warning light would come on. Mechanics would find the SCR system's injectors and filters completely clogged, costing 5,000-6,000 yuan to clean and replace. Diluting urea causes crystals to form, blocking the entire exhaust after-treatment system. Now I strictly adhere to the 32.5% concentration standard by purchasing bottled automotive-grade urea solution. Saving small amounts could lead to tens of thousands in repair costs. Long-term water mixing can also destroy the catalytic converter, and failing emissions tests with environmental fines would be even more costly.
Having worked in a repair shop for eight years, I've handled over a dozen cases of urea system failures caused by water dilution. Automotive urea must be mixed with deionized water to achieve a 32.5% concentration - calcium and magnesium ions in tap water can crystallize and clog the injectors. Last month, a customer poured 30% tap water into the urea tank, resulting in torque limitation when climbing hills, with the diagnostic tool showing NOx sensor errors. These systems are precision-engineered; water dilution causes crystalline blockages in the pipelines, and insufficient concentration triggers OBD alerts. I recommend using prepackaged urea solution - don't risk damaging the entire SCR system to save small costs.
