What is the reason for the urea tank not making a clicking sound after parking?

[Jennifer]

When there is no sound after parking, it indicates a malfunction in the urea pump. The urea pump continues to operate after the engine is turned off to pump the unused urea in the pipes back into the urea tank. Otherwise, the urea in the pipes may crystallize, affecting normal use the next time. Therefore, the urea pump will continue to work for a while after the engine is turned off before stopping on its own. Below is an introduction to the urea pump: 1. Working principle and internal composition of the urea pump The urea pump is the core component of the SCR system, known as the "urea metering pump." Its main function is to pump the urea solution from the urea tank and transport it to the nozzle through the delivery pipe. 2. Working principle of the urea pump The internal composition of the urea pump mainly consists of a diaphragm pump, electromagnetic reversing valve, pressure sensor, urea filter, electric heating system, and lead frame. The exterior is composed of three urea solution pipelines: the injection pipe, return pipe, and inlet pipe. 3. Internal composition of the urea pump There are two types of urea pumps: one is the airless urea pump represented by Bosch, and the other is the air-assisted urea pump represented by Emitec and Cummins.

[VonChase]

I just encountered the issue of the urea tank not making any sound after parking, which is quite concerning because the usual ticking sound during parking is normal. Possible reasons include the solenoid valve being stuck or clogged—over time, I've noticed urea crystallization can block the valve's movement. It could also be that the system detected the urea level was too low and automatically stopped the injection, so you might want to first check if the urea tank's fluid level is normal. Another possibility is a control module malfunction, such as a faulty sensor sending incorrect signals. Wiring issues are also common, like loose connectors or blown fuses—my neighbor's car once had a problem due to a blown fuse. Don’t underestimate this issue; if left unrepaired, the SCR system might fail, leading to excessive emissions that harm the environment, or even triggering vehicle speed limitations. For safety, it’s best to check the fluid level yourself and visit a repair shop as soon as possible to diagnose and fix any electrical faults.

[MargaretDella]

As someone who frequently repairs vehicles, there are typically three reasons for a silent urea tank after parking: First, insufficient urea level triggers system protection and prevents the valve from opening. Check the fluid level and refill if it's below the marked line. Second, the solenoid valve or pump may be damaged or stuck. I recommend using a test light to check the circuit voltage to see if the power supply is normal. If there's no power, it could be a blown fuse or relay failure. Third, control unit faults, such as sensor errors, require reading the trouble codes for confirmation. In practice, urea impurities often clog components, and after parking, the system should purge nitrogen but remains silent due to clogging, which is easily overlooked but poses a significant risk, potentially leading to DPF clogging and increased repair costs. If you're handy, you can perform a simple self-check on the fuse box or connectors; otherwise, quickly seek a professional technician to avoid torque limitation issues that could affect daily use and safety.

[JasperRose]

The urea tank not making a ticking sound after parking might be fine as the system automatically goes into sleep mode. However, if it should be ticking but isn't, it could be due to the solenoid valve not working or insufficient urea. Pay attention when the dashboard warning light is on, as the control module might be faulty. The absence of sound could also be caused by loose electrical connections, which can be easily fixed, but it's recommended to regularly add high-quality urea to prevent scaling. Delaying repairs can lead to excessive emissions, harming the environment, and in worse cases, the ECU may limit engine power, increasing danger. Timely checks can prevent minor issues from becoming major expenses.