Why Gas coming thru exhaust?

Gas coming through the exhaust can indicate several issues, primarily related to the combustion process within the engine. Common reasons include incomplete combustion, which can lead to unburnt fuel or oil entering the exhaust system. Additionally, a malfunctioning catalytic converter or issues with the engine's air-fuel mixture can also cause excessive gases to escape through the exhaust. It's important to diagnose the specific cause to avoid potential damage to the engine or exhaust system.