Can O2 and CO readings be high at the same time?

In evaluating the relationship between O2 (oxygen) and CO (carbon monoxide) readings in an engine's exhaust, it is important to understand the combustion process and how these gases are typically produced. Oxygen is a byproduct of the combustion process when there is an excess of air, and it levels can remain high if the air-fuel mixture is too lean. Conversely, carbon monoxide is produced when there is incomplete combustion, often due to an air-fuel mixture that is too rich.

Under normal operating conditions, it is not feasible for both O2 and CO levels to be high simultaneously. High readings of carbon monoxide generally indicate a lack of sufficient oxygen in the combustion process, leading to incomplete combustion. Therefore, if CO levels are high, O2 levels would typically be low because the combustion process is not utilizing the available oxygen efficiently.

The assertion that both readings can be high at the same time is therefore incorrect, making the answer that denotes this scenario as false accurate. Understanding this fundamental relationship is crucial for diagnosing engine performance issues and ensuring optimal combustion efficiency.