Can dirty gas cause the check engine light to come on 2006 Saturn?

Yes, dirty gas in a 2006 Saturn (or any car) can absolutely cause the check engine light to come on. Dirty gas can contain contaminants that clog fuel injectors, damage oxygen sensors, or otherwise disrupt the fuel system's proper operation. These problems will often trigger a diagnostic trouble code (DTC) that illuminates the check engine light. The specific code will depend on the precise nature of the problem.