The diesel exhaust fluid (DEF) light, also known as the “AdBlue” light, is a warning light that can appear on the dashboard of many diesel vehicles. This light typically illuminates when there is a problem with the DEF system, which is responsible for reducing emissions of nitrogen oxides (NOx) in diesel engines.
In this article, we will discuss what the DEF light means, and how to diagnose the problem using an on-board diagnostic (OBD) device.
The DEF light is typically illuminated when the DEF level is low, or when there is a problem with the DEF system. The DEF system is a component of the emissions control system that uses a solution of urea and water to reduce the amount of NOx in the exhaust gases. When the DEF level is low, or when there is a problem with the system, the engine’s performance may be limited and the DEF light will be illuminated.
When the DEF light illuminates, it is important to diagnose the problem as soon as possible. One way to do this is by using an OBD device. OBD devices are diagnostic tools that can be plugged into the vehicle’s OBD-II port, which is typically located under the dashboard. The device can then read diagnostic trouble codes (DTCs) that have been stored in the vehicle’s computer, which can indicate the cause of the DEF light.
Common causes of the DEF light include a low DEF level, a malfunctioning DEF sensor, or a problem with the DEF injector. A low DEF level can be caused by a variety of factors, including a leak in the system or simply forgetting to refill the DEF tank. A malfunctioning DEF sensor can also cause the light to illuminate, and this can be caused by a variety of factors, including a problem with the sensor’s wiring or a problem with the sensor itself. A problem with the DEF injector can also cause the light to illuminate, and this can be caused by a variety of factors, including a clogged injector or a problem with the injector’s wiring.
To diagnose the problem, an OBD device can be used to read the DTCs and troubleshoot the issue. The device can also be used to clear the DTCs and reset the system once the problem has been resolved.
In conclusion, the diesel exhaust fluid (DEF) light, also known as the “AdBlue” light, is a warning light that can appear on the dashboard of many diesel vehicles. This light typically illuminates when there is a problem with the DEF system, which is responsible for reducing emissions of nitrogen oxides (NOx) in diesel engines.
If the light illuminates, it is important to diagnose the problem as soon as possible, using an OBD device, to read the DTCs and troubleshoot the issue. Once the problem has been resolved, the device can also be used to clear the DTCs and reset the system. It’s also important to regularly check the DEF level and to have the vehicle checked by a professional.