What does it mean when the DEF light comes on in a diesel vehicle?
2 Answers
When the DEF light comes on in a diesel vehicle, it indicates that the vehicle's urea is running low and reminds the owner to add urea as soon as possible. Below is the relevant information: 1. Introduction to DEF: DEF (Diesel Exhaust Fluid) is referred to as diesel exhaust treatment fluid. 2. Function of DEF: Diesel exhaust treatment fluid (commonly known in China as automotive urea, vehicle urea, or automotive environmental urea) is a consumable required in SCR technology. It is a liquid used in SCR technology to reduce nitrogen oxide pollution in diesel vehicle exhaust. Its composition consists of 32.5% high-purity urea and 67.5% deionized water.
When the DEF indicator on the dashboard of my diesel vehicle lit up, I immediately realized there was an issue with the emission system. DEF stands for Diesel Exhaust Fluid, and the light indicates either insufficient urea fluid level or abnormal system operation. During a long-distance trip, when this light suddenly came on, I promptly pulled over to check the urea tank level and found it below the minimum line. A lack of urea can lead to excessive emissions, and worse, the vehicle will automatically enter a speed-limiting mode. Being suddenly restricted to just 30 km/h on the highway is dangerous. I quickly added a bottle of urea solution, but the light remained on, suggesting a possible nozzle clog or temperature sensor malfunction. It's crucial to visit a repair shop as soon as possible to read the fault codes with a diagnostic tool. Never delay addressing this issue, as damaging the catalytic converter would result in even costlier repairs.
