Why is the SINOTRUK HOWO National V urea fault light on?
2 Answers
There are many situations where faults may occur. The specific reasons for the fault are as follows: Unqualified urea quality: The vehicle is weak, and urea consumption is normal. After urea crystallization fails, a large amount of urea is stored in the exhaust pipe, which not only causes engine exhaust blockage and inability to work properly but also results in excessive emissions. Urea tank temperature is too high: The high temperature of the urea tank causes urea to volatilize and be discharged from the exhaust port, crystallizing around the tank. Excessive crystallization at the exhaust port leads to blockage. During the operation of the urea system, severe vacuum suction in the urea chamber causes urea pressure buildup blockage, resulting in low urea pressure faults. Insufficient power, urea pump power supply module corrosion: Urea consumption is too high or too low, urea pump pressure sensor high-pressure signal, actuator ground short circuit, urea reversing valve actuator opening, sensor power supply error. There is a large range of corrosion, causing the power module to insert the wiring harness to connect to the power supply and send incorrect voltage value signals to the ECU.
I've been driving trucks for over a decade and encountered the urea warning light issue on my HOWO China V emission standard truck several times. Generally, this light indicates a problem with the SCR system, most commonly due to low DEF (AdBlue) fluid level which requires immediate refill. If the fluid level is normal, it might be caused by dirty or damaged sensors, such as dust clogging the probe. Once when the light came on, the truck immediately experienced power loss and became very sluggish to drive. Ignoring it could put the vehicle into limp mode, which is dangerous even on highways. Other possible triggers include loose wiring or DEF pump failure. For basic checks, inspect the DEF tank first. If the fluid level is adequate, avoid tampering with sensors yourself and head straight to a repair shop for professional diagnostic scanning. Timely attention can prevent engine damage and save repair costs. Regular DEF refills and injector cleaning during routine maintenance will help minimize occurrences of this warning light.
