What Causes Excessive Carbon Monoxide in Exhaust?

[McDallas]

Reasons and solutions for excessive carbon monoxide in exhaust are as follows: 1. Oxygen sensor is dirty, requiring replacement or cleaning; 2. Three-way catalytic converter is damaged, needing repair or replacement; 3. Remove carbon deposits from the intake and exhaust systems, clean the throttle body and fuel injectors, and replace if necessary; 4. Check spark plug gap deviation and correct or replace; 5. Inspect vacuum tubes for leaks or blockages and address accordingly; 6. If coolant temperature is too high, repair the cooling fan to restore normal operation; 7. Use an OBD scanner to check if the intake pressure sensor is functioning properly.

[VonAustin]

I recently noticed that the carbon monoxide level in my car's exhaust is higher than normal, which is quite concerning. The main reason is usually that the air-fuel mixture is too rich, meaning the fuel isn't burning cleanly enough. This could be due to a clogged air filter restricting airflow, or leaking fuel injectors causing excessive fuel supply—more fuel leads to incomplete combustion and higher carbon monoxide emissions. Additionally, internal engine wear, such as worn piston rings failing to seal properly, can also reduce combustion efficiency. I checked it myself and started by cleaning the air filter to see if that would help save money. Using low-quality gasoline might also contribute to this issue, so switching to higher-octane fuel is recommended. It's important to avoid engine overheating during daily driving and perform regular maintenance to minimize problems. If you frequently notice unusual odors in the exhaust, get it checked promptly—delaying not only pollutes the environment but may also damage the catalytic converter.

[McSara]

From my years of experience in car repair, excessively high carbon monoxide levels in exhaust are most commonly caused by an imbalanced air-fuel ratio. This happens when there's too much fuel or too little air. For example, a faulty oxygen sensor, which is supposed to regulate the mixture, fails to function properly, leading to incomplete combustion. Leaking fuel injectors or excessively high fuel pressure can also exacerbate this issue. When too much fuel is injected, there isn't enough oxygen in the combustion chamber, resulting in the production of excessive carbon monoxide. Additionally, if the catalytic converter is aged or clogged and can't efficiently convert emissions, carbon monoxide will accumulate in the exhaust. I recommend first using an OBD diagnostic tool to read the fault codes and check the status of these components. Repairs are relatively straightforward—for instance, replacing a faulty sensor can resolve most of the issue. In daily driving, avoiding sudden acceleration and prolonged idling can help reduce CO emissions.

[ElleAnn]

I'm particularly concerned about the issue of carbon monoxide in exhaust emissions, as it not only pollutes the air but also poses health hazards. The primary cause is often incomplete combustion in the engine, such as malfunctioning ignition systems, delayed sparking from worn-out spark plugs, or unburned fuel being expelled, which naturally increases CO levels. A clogged air filter that hasn't been replaced for too long restricts air intake, and insufficient oxygen exacerbates emissions. This directly leads to exceeding emission test limits, which are strictly regulated by national environmental standards. Individuals can contribute by taking small actions, such as regularly checking catalytic converter functionality and fuel quality, and opting for low-sulfur fuels to reduce CO production. Small changes accumulated can help the planet reduce pollution.