What is the reason for the absence of urea reflux sound after engine shutdown?
2 Answers
After engine shutdown, the absence of urea reflux sound may be caused by a malfunction in the urea recovery device, and it should be inspected and repaired at a 4S shop as soon as possible. Below is relevant information about automotive urea: 1. The role of automotive urea: Generally, adding urea to vehicles is primarily to reduce exhaust emissions, as diesel engine exhaust mainly consists of nitrogen oxides and carbon particles. 2. National regulations: Because vehicle exhaust emissions pose significant harm to both people and the environment. Therefore, the National IV standard implemented in 2008 in China stipulates that diesel vehicles must use automotive urea in their emission reduction systems.
I've been driving diesel vehicles for over twenty years, and I know there should be that 'gurgling' sound after turning off the engine, indicating the urea pump is recirculating excess fluid. If there's no sound, it's a pretty common issue. Most of the time, it's a problem with the pump itself, like a seized motor or internal freezing/scale buildup. Once, my car had this issue, and it turned out the urea froze in low winter temperatures, blocking the pipes—just blowing some warm air fixed it. It could also be incorrect sensor signals causing the pump not to work. I suggest first checking if the urea level is sufficient; if it's too low, the system will shut down. Then, see if there's any fault code on the dashboard. If left unfixed, over time, the urea system may fail, and the engine might go into torque reduction mode, making the car sluggish and fuel-inefficient. Before parking, try pressing the brake pedal a few times to force the system to activate. If there's still no sound, it's best to get a full check at a 4S shop for the pump and wiring. Small issues might cost a few hundred bucks, but delaying could make it more expensive.
