The frequency of catalyst system inspections can vary depending on various factors such as the vehicle's age, mileage, and overall condition. As a general guideline, it is recommended to have your catalyst system inspected during routine maintenance services, which are typically performed every 12,000 to 15,000 miles or as specified by the vehicle manufacturer. Additionally, if you experience any symptoms of catalyst system issues, such as the illumination of the Check Engine Light, decreased engine performance, increased fuel consumption, or unusual odors, it is crucial to have the system inspected promptly. Timely inspections and maintenance can help identify potential problems early on and prevent further damage or costly repairs. Consult your vehicle's owner's manual or seek advice from a qualified mechanic to determine the specific inspection intervals that are appropriate for your vehicle.