Where is the Problem When Car Exhaust Smells Pungent?
2 Answers
Exhaust fumes often smell pungent when the car is cold and just started, because the three-way catalytic converter is still at a low working temperature. The effective working temperature range for a three-way catalytic converter is between 400 to 800 degrees Celsius. Below 400 degrees, it cannot perform catalytic functions effectively, resulting in higher emissions of hydrogen sulfide. Some of these gases may enter the car's interior through the air conditioning circulation system. Introduction to Car Exhaust: Car exhaust refers to the waste gases produced during vehicle operation, containing hundreds of different compounds. Pollutants in exhaust include solid suspended particles, carbon monoxide, carbon dioxide, hydrocarbons, nitrogen oxides, lead, and sulfur oxides, among others. Hazards of Car Exhaust: In addition to directly harming human health, car exhaust also has profound impacts on the environment. Sulfur dioxide in exhaust has a strong irritating odor and, when reaching certain concentrations, can lead to "acid rain," causing soil and water sources to acidify and affecting the growth of crops and forests.
Last year, my old car had exhaust fumes that smelled extremely pungent, like rotten eggs. After checking, I found out it was due to a faulty catalytic converter—it purifies exhaust gases, but when it degrades, it releases harmful emissions. Additionally, if the oxygen sensor is inaccurate, it can cause the air-fuel mixture to be too rich, leading to incomplete combustion and foul odors. A dirty air filter can also cause this issue—I took mine apart and found the filter completely clogged with dust; replacing it fixed the problem. If the smell is strong while driving, there might also be an exhaust leak due to rusted pipes or loose connections. My advice is to start with the simplest fix: check if the air filter is clean. If that doesn’t help, take it to a repair shop for diagnostics—don’t ignore it, as it’s bad for your health and the environment, especially in cities where opening windows makes it worse. Regular maintenance is key to prevention, and replacement parts usually cost just a few hundred bucks.
