What Causes Excessive Carbon Monoxide in Car Exhaust?
3 Answers
There are several main reasons for excessive carbon monoxide in car exhaust: 1. Sensor malfunction: A faulty sensor that controls and stabilizes the air-fuel ratio can cause excessive gasoline injection, resulting in insufficient air supply. This leads to incomplete combustion of gasoline, increasing carbon monoxide levels in the exhaust. 2. Clogged or dirty catalytic converter: This can render the catalytic converter incapable of converting carbon monoxide, requiring cleaning or replacement. 3. Excessive carbon buildup: Simply cleaning the carbon deposits to ensure complete fuel combustion and prevent carbon buildup in the engine can significantly reduce carbon monoxide in the exhaust.
I've encountered many cases of excessive exhaust emissions while repairing cars, and there are numerous reasons for high carbon monoxide levels. The main cause is incomplete combustion, where gasoline isn't fully burned before being expelled. For example, a clogged air filter prevents the engine from drawing in enough oxygen; a faulty oxygen sensor sends incorrect data to the engine control unit, leading to an imbalanced air-fuel mixture with too much fuel and too little air; spark plug carbon buildup causes misfires and reduces combustion efficiency; a failed catalytic converter can't transform pollutants; and even exhaust system leaks can interrupt combustion. I once dealt with an old car that had severe emission issues and couldn't pass the annual inspection—it turned out to be a faulty oxygen sensor causing a rich mixture, which was resolved after replacement. Excessive emissions are harmful: they pollute the air, cause inspection failures, and may accelerate engine wear. Don't skimp on regular maintenance: change the air filter periodically, check the sensors, and ensure the system functions properly. Delaying repairs only makes things worse. I recommend getting a full inspection at a repair shop as soon as issues are detected.
Last time my car had the same issue - failed the annual inspection due to excessive exhaust emissions. The report indicated high carbon monoxide levels. The mechanic explained it was caused by incomplete combustion, like when the air-fuel mixture is too rich (more gasoline, less air). Possible reasons include a clogged air filter restricting airflow or a faulty oxygen sensor causing the ECU to incorrectly adjust fuel injection. In my case, it was due to sensor aging - replacing it fixed the problem. Other common causes include: inaccurate spark plug ignition timing, or a damaged catalytic converter failing to purify emissions. Exceeding emission limits makes exhaust smell pungent and pollutes the environment, causing inspection failure. It may also cause engine hesitation while driving. So I've learned my lesson - perform regular maintenance, replace wear-prone parts like injectors and throttle bodies during inspections, and address minor issues promptly before they escalate.
