What to Do When Urea is Not Consumed and Torque is Limited?
4 Answers
The methods to address the issue of urea not being consumed and torque being limited are as follows: 1. Check whether the post-processing wiring harness and sensors are properly connected, and make adjustments or repairs if any issues are found. 2. Inspect the urea pipeline for any leaks or abnormalities, and replace it promptly if necessary. 3. Verify the normal operation of the urea pump; if any malfunction is detected, promptly investigate the cause of the fault. 4. Examine the urea nozzle to ensure it is functioning correctly; if the nozzle is clogged or fails to open properly, clean or replace it immediately. When a vehicle does not consume urea, the problem often involves not just one fault code but a series of fault codes, requiring systematic troubleshooting. A service station diagnostic tool can be used to check the relevant codes. If the vehicle does not use urea or uses products of insufficient purity or inferior quality, the engine's torque output will be limited. Additionally, inferior-quality urea can contaminate the catalyst in the SCR catalytic reaction tank, leading to severe consequences. Therefore, it is essential to use high-quality urea products. If it is found that the vehicle is not consuming urea, timely maintenance should be performed.
I've fixed quite a few truck buddies' vehicles with this same issue. The most critical problem is when the urea pump gets clogged and the nozzle can't spray liquid. Try turning the key off and restarting a few times—if you're lucky, the liquid supply might resume. Last time, Brother Li's tractor trailer ignored the yellow warning light and ended up with a 30% torque limitation on a long haul, sweating bullets in panic. When we finally opened the urea tank, we found the filter screen completely clogged with crystallized low-quality urea, and the high-pressure pump was burnt out. It's kind of like treating a cold—catch it early, and you might just spend a few hundred cleaning the lines. Ignore it, and you're looking at replacing the entire pump assembly, easily running over two to three thousand. Always keep a bucket of good-quality urea in the trunk for emergencies. Sure, service stations charge more, but it could save your life.
Last month, I also encountered this annoying issue while driving a construction vehicle. First, don’t rush to the repair shop—check three things yourself: 1) Check if the urea level on the dashboard is empty or falsely reported, 2) Crawl under the vehicle to listen for a humming sound from the urea pump, and 3) Observe whether the exhaust pipe emits white smoke at 2,500 RPM (it normally should). Old Zhang from our fleet had a faulty temperature sensor, causing the ECU to misjudge sub-zero temperatures and stop urea injection—replacing the sensor for 800 yuan fixed it. However, if you smell a pungent ammonia odor, the nozzle is likely cracked, and you should stop driving immediately to prevent exhaust pipe corrosion.
In my fifth year of driving a diesel pickup, I finally realized: not using urea is like your kidneys going on strike, and the engine will protest by limiting your speed. Focus on checking three areas: the urea tank heater (it fails a lot in winter), the nozzle and pipes (feel the hoses for any crystallized blocks), and the DCU control module (check if the golden fingers are oxidized by unplugging it). Last week, my cousin cheaped out and used off-brand urea, which caused the pipes to freeze and crack, costing him 4,200 RMB to fix. My advice: every 30,000 kilometers, remove the nozzle and soak it in warm water for two hours—it saves you 800 RMB compared to buying a new one.
