How to Solve Only NO Exceeding the Standard?
2 Answers
If the NO level in the exhaust gas is significantly exceeded, the first step is to clean the cooling system and the heat dissipation system, and even flush the lubrication system. Here are some related introductions about exhaust gas: Control the flow rate of the cleaning agent: The flow rate of the cleaning agent should be controlled to the point where the engine idles with slight vibration as the optimal condition. If the engine vibrates severely during the cleaning process, immediately reduce the flow rate of the cleaning agent. Some 4S shop technicians, aiming for speed, inject the cleaning agent into the engine at a high flow rate, which not only damages the engine but also reduces the cleaning effect. Cleaning of the three-way catalytic converter: The three-way catalytic converter should be cleaned and maintained every 30,000 kilometers, and those with the means can clean it every 10,000 kilometers. Under normal maintenance conditions, the service life of the three-way catalytic converter is between 150,000 kilometers and 200,000 kilometers before replacement is needed.
When my vehicle's emissions test shows only excessive NOx levels, I first check several common points. High NOx typically indicates an issue with the exhaust system, such as an aging or failing catalytic converter or a sluggish oxygen sensor. An overly rich air-fuel mixture in the engine can also cause NOx levels to rise. I usually start with the simpler fixes: removing the oxygen sensor to check for carbon buildup, cleaning it, or replacing it with a new one; then inspecting the catalytic converter—if it makes no sound when tapped or the exhaust pipe is abnormally hot, it’s likely internal damage requiring replacement. The engine control unit may also need recalibration, which requires a reliable repair shop with a diagnostic tool for adjustment. Don’t forget to check the air filter and fuel system for dirt, as blockages can affect combustion efficiency. Regular maintenance of the catalytic converter can extend its lifespan. Ignoring this issue will not only fail the annual environmental inspection but also harm the environment—address it early to drive with peace of mind.
