Failed catalytic converter why

When the hot exhaust passes these elements a chemical transformation occurs. It is a simple structure with no moving parts and only requires the heat of the exhaust and the right exhaust gas mixture to operate.

Inside the catalytic converter: the "honeycomb" substrate. Catalytic converter failures occur in several ways: First, impact failures which can occur if the unit is hit, often involving running over something. Second, thermal shocks which can occur if the unit is suddenly cooled. Reduced Engine Performance One of the first symptoms commonly associated with a bad or failing catalytic converter is a reduction in engine performance.

Rattling Noise Rattling noises from under the vehicle are another symptom of a bad or failing catalytic converter. Sulfur Smell from Exhaust During engine combustion, sulfur-containing gasoline becomes hydrogen sulfide.

Failed Emissions Test Some states in the U. Home Exhaust and Emission System Inspection. The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details. Excellent Auto Repair Ratings. YourMechanic Auto Repair. Related Articles.

Experienced Mechanic? Recent Exhaust and Emission System Inspection reviews. Excellent Rating. Rating Summary. Diego 21 years of experience. Request Diego. Pontiac Grand Am L Diego was very Professional, kind and explained everything to us about his diagnosis.

We felt confident in his assessment and booked him for the appt. Normally, some evidence of impact is visible on the converter shield. Other conditions that may potentially cause structural damage:. The content contained in this article is for informational purposes only and should not be used in lieu of seeking professional advice from a certified technician or mechanic.

We encourage you to consult with a certified technician or mechanic if you have specific questions or concerns relating to any of the topics covered herein. Under no circumstances will we be liable for any loss or damage caused by your reliance on any content. Technical Resources. This happens because of piston rings that lose their ability to properly seal as the miles pile up, or because a valve becomes stuck.

It can also be due to any number of small design issues or worn-out engine components. Black smoke or signs that your car is using a significant amount of oil in between changes are indicators that you may end up reducing the efficiency of — or even permanently damaging — your converter. Photo courtesy of Wikimedia Commons. Know How. Having been bitten by the car bug at a young age, I spent my formative years surrounded by Studebakers at car shows across Quebec and the northeastern United States.