Your catalytic converter is part of your car’s emissions system, but its job goes far beyond just reducing pollutants. When it starts to clog, you might notice your engine struggling, your fuel efficiency dropping, or strange smells from the exhaust. These symptoms are easy to overlook at first, but letting the issue go too long can lead to bigger performance problems or even damage to other parts of your vehicle. So, how do you know if your catalytic converter is starting to fail?
Slow Acceleration or Loss of Power
One of the earliest signs of a clogged catalytic converter is a noticeable loss of power—especially during acceleration or uphill driving. If the converter is blocked, it creates excessive backpressure in the exhaust system, restricting your engine’s ability to “breathe.” That restriction can lead to sluggish throttle response and poor overall performance.
If your car feels like it’s working harder than usual but going nowhere fast, it could be time to get the exhaust system checked.
Poor Fuel Efficiency
When your engine can’t efficiently push out exhaust gases, it has to work harder to maintain speed and power. That additional strain often leads to increased fuel consumption. If you’re filling up more often than usual and haven’t changed your driving habits, a failing catalytic converter could be the culprit.
Don’t just blame it on gas prices—any unexplained drop in MPG deserves a closer look.
Check Engine Light Is On
Your vehicle’s onboard diagnostics system monitors the catalytic converter’s performance through oxygen sensors. If the system detects poor efficiency or abnormal readings, it may trigger the check engine light. Common trouble codes include P0420 (Catalyst System Efficiency Below Threshold), which often points to a failing or clogged converter.
A scan of your OBD system at a repair shop can confirm whether your catalytic converter is involved and whether it’s time to replace it.
Rattling Noises Under the Car
If the internal structure of your catalytic converter breaks down, pieces of the ceramic honeycomb inside can loosen and rattle around. You’ll typically hear a metallic rattling sound—especially when starting the car or accelerating. This is a clear sign that the converter is damaged and may be clogged or completely failing.
Ignoring these noises can eventually lead to a total blockage or further damage to your exhaust system.
Rotten Egg Smell from the Exhaust
A sulfur or rotten egg odor coming from your tailpipe is another classic sign of a failing catalytic converter. This smell comes from unprocessed hydrogen sulfide in your exhaust, which should normally be converted into odorless sulfur dioxide. If the converter isn’t doing its job, the smell becomes very noticeable—and it’s a good sign that the system needs attention.
Excessive Heat from Under the Vehicle
When exhaust gases can’t flow properly through a clogged converter, heat builds up in the exhaust system. You might notice extreme warmth under the floorboard or near the engine bay. In some cases, this heat can damage nearby components or lead to a fire hazard if left unchecked.
We can use an infrared thermometer to compare inlet and outlet temperatures to determine if your catalytic converter is overheating.
DRIVE AutoCare – Exhaust System Experts in Solana Beach, CA
Suspect a clogged catalytic converter? At DRIVE AutoCare, with two locations in Solana Beach, CA, we can help diagnose and repair emission system problems. Whether it’s a drop in performance, a check engine light, or strange odors from your tailpipe, our experienced technicians can get to the root of the issue and restore your car’s efficiency.