How to Tell if the Catalytic Converter Has Been Removed?
2 Answers
You can check by its appearance. A normal catalytic converter should have uniformly arranged and evenly sized pores in its internal porous ceramic, which should also be clean and relatively white (a yellowish beige color indicates a counterfeit). The porous ceramic inside the catalytic converter serves as a carrier and should be firmly and securely assembled with the outer shell, with no signs of looseness. A replacement catalytic converter should match the original factory specifications in terms of size, the material of the internal porous ceramic, the arrangement of the pores, and the number of rows. Additional information: 1. The catalytic converter is the most important external purification device installed in a car's exhaust system. It converts harmful gases such as CO, HC, and NOx emitted from the car's exhaust into harmless carbon dioxide, water, and nitrogen through oxidation and reduction reactions. 2. When high-temperature exhaust gases pass through the purification device, the catalyst in the catalytic converter enhances the activity of CO, HC, and NOx, promoting specific oxidation-reduction chemical reactions. CO oxidizes at high temperatures into colorless, non-toxic carbon dioxide gas; HC compounds oxidize into water (H2O) and carbon dioxide; and NOx is reduced into nitrogen and oxygen. These three harmful gases are transformed into harmless gases, thereby purifying the car's exhaust.
When I first got into cars, I didn't understand catalytic converters. But one time while driving, I noticed the exhaust sounded shockingly loud, like a race car roar—it had never been that noisy before. After parking, I smelled a strong sulfur or gasoline odor at the rear, much heavier than normal exhaust. Peeking under the chassis, I saw the mid-section of the exhaust pipe was empty where a cylindrical metal block should have been—turns out the catalytic converter had been removed. A friend told me it reduces pollution; removing it might slightly boost performance but drastically increases emissions. Sometimes, the yellow emissions warning light would come on, and OBD scans often showed a P0420 code. In short, the changes in sound, smell, and visual inspection were obvious but harmful, so prompt repair is crucial.
