Two common signs that a catalytic converter may have failed are a Check Engine Light with emission-related diagnostic codes (often P0420 or P0430) and a noticeable drop in engine power along with poorer fuel economy.
Common symptoms
Here are the two symptoms explained in more detail for readers assessing vehicle performance.
- Check Engine Light and diagnostic trouble codes: The onboard computer monitors catalytic converter efficiency and will illuminate the check engine light if it detects the converter is not meeting emissions standards. Common codes include P0420 (Catalyst System Efficiency Below Threshold) and P0430 (Catalyst System Efficiency Below Threshold for Bank 2).
- Loss of power and reduced fuel economy: A failing catalytic converter can create backpressure in the exhaust, making the engine work harder and resulting in slower acceleration and higher fuel consumption, especially during rapid throttle needs like merging or climbing hills.
If you notice either symptom, arrange a professional diagnostic as soon as possible. A degraded catalytic converter can lead to increased emissions, damage to the exhaust system, and the risk of failing an emissions test.
Summary
In short, the two most common symptoms of a failed catalytic converter are a Check Engine Light with codes such as P0420/P0430 and a palpable loss of power with reduced fuel economy. Timely inspection and repair by a qualified mechanic can prevent further damage and help ensure the vehicle remains compliant with emissions standards.