Will the Malfunction Indicator Light Turn On If the Three-Way Catalytic Converter Fails?
2 Answers
A faulty three-way catalytic converter can cause the malfunction indicator light to illuminate. The three-way catalytic converter is the most important external purification device installed in a vehicle's exhaust system. Methods to determine the condition of the three-way catalytic converter: Visual Inspection. Examine the exterior of the three-way catalytic converter for any damage or discoloration. Scratches, cracks, or other visible damage may indicate that the converter has been compromised. If there are noticeable gray spots in the center of the converter's protective cover, severe discoloration, or purple marks on the shell, it may suggest overheating issues. Check the Engine Exhaust. Place your hand near the tailpipe outlet to feel the exhaust flow and assess whether the three-way catalytic converter is clogged or if there are any exhaust flow issues. Another method is to open the air filter, remove the filter element, and observe if there is any exhaust backflow during rapid acceleration, which would indicate poor exhaust flow. To evaluate the condition of the TWC (Three-Way Catalyst), also check if the secondary air injection pump is functioning properly. Use an Infrared Thermometer. Compare the temperature difference between the front and back of the TWC using an infrared thermometer. If the temperature difference between the inlet and outlet of the three-way catalytic converter is less than 10°C, the TWC is likely damaged.
If the catalytic converter is faulty, the check engine light might indeed come on. I recently experienced this issue with my own car—the light suddenly turned yellow, and the diagnostic tool showed a code for low catalytic efficiency. It turned out that the honeycomb structure inside the converter was clogged, causing poor exhaust flow. The car was often used for short trips, and the engine didn’t reach optimal temperature before shutting off, leading to severe carbon buildup. It’s advisable to address this promptly; otherwise, not only will emissions fail to meet standards, but fuel consumption will also spike. However, keep in mind that a lit check engine light isn’t always due to the catalytic converter—issues like a faulty oxygen sensor or wiring problems can trigger similar warnings. The best approach is to get a professional inspection at a repair shop rather than guessing and delaying repairs.
