AdBlue® is the registered trademark for AUS32 (Aqueous Urea Solution 32.5%) and is used in a process called selective catalytic reduction (SCR) to reduce emissions of oxides of nitrogen from the exhaust of diesel engined motor vehicles. It is also referred to as DEF (Diesel Exhaust Fluid). It is a 32.5% solution of high-purity urea in demineralised water that is clear, nontoxic and safe to handle. However, it can be corrosive for some metals and must be stored or transported using the correct materials. This tester has been designed to allow the DEF to be tested for urea strength. In order for the diesel engine emissions system to function correctly the strength of the DEF solution must be maintained at 32.5% urea; over time the strength of the solution can change by 1. evaporation causing the water component of the solution to reduce, or 2. contamination. Either of these can cause variations in DEF quality and strength which will be flagged up by the engine’s on board diagnostic system (DEF warning light). This tester is extremely easy to use and displays a clear pass or fail result regardless of the temperature of the sample. This tester is suitable for all diesel-engined vehicles (commercial or passenger) that use DEF.