If your car is not acting like it should, catalytic converter failure may not be the first thing that comes to mind. However, the signs of a bad catalytic converter are easy to identify, and you can implement some checkpoints in your car maintenance routine to keep your catalytic converter operational.

What Does a Catalytic Converter Do?

A catalytic converter catalyzes — breaks down — unburned gases into less damaging emissions during the combustion process. Cars produce potentially dangerous emissions, such as:

  • Sulfur dioxide
  • Nitrogen dioxide
  • Ozone
  • Lead
  • Hydrocarbons
  • Carbon monoxide

The inside of a catalytic converter has a honeycomb structure lined with precious elements like platinum, rhodium and palladium. These elements turn emissions into safer substances like oxygen, water and carbon dioxide to reduce pollution and improve air quality.

Catalytic converters have been the standard for decades, first introduced to gas-powered cars in the 1970s. As car manufacturers learned more about the harmful effects of emissions on the environment, they implemented catalytic converters in the exhaust system to defend against air pollution.

Importance of a Functional Catalytic Converter

A catalytic converter is an essential part of your exhaust system, so there are many reasons you should ensure this component is functional.

If a catalytic converter stops working, it can harm the environment because the converter can't reduce air pollution. This buildup of pollutants could cause your car to fail emissions testing and standards.

Your car will not run and drive like usual if the catalytic converter doesn't work. A clogged catalytic converter can overheat and cause blown engine seals and oil leaks. These issues can cause engine failure, and rebuilding or replacing your engine can be costly.

Problems with your catalytic converter will not go away on their own, so be aware of catalytic converter failure symptoms and take care of the problem as soon as possible.

Common Signs of a Bad Catalytic Converter

A catalytic converter can get plugged, develop clogs or otherwise not work as it should. You know your catalytic converter is bad if you notice that:

  • The check engine light is on: The internal computer in your car monitors exhaust gas levels and will trigger the check engine light if the sensor notices a problem. The check engine light can turn on if your catalytic converter is bad.
  • The engine is noisy: A clogged catalytic converter can make a rattling noise when starting your car, idling or driving. Heat damage can cause the honeycomb structure to break apart and create noise.
  • The engine misfires: A bad catalytic converter causes incomplete combustion in the firing cylinders. This problem can cause engine misfires and make it difficult to start your car.
  • Heat is building up under your car: A bad catalytic converter can cause extreme heat to build up under your vehicle. This symptom is dangerous because the heat could make your car catch on fire.
  • The exhaust has a sulfur or rotten egg smell: Catalytic converters shouldn't smell, but they can produce a foul odor when malfunctioning. This smell is both unpleasant and dangerous — inhaling these gasses can make you feel lightheaded, which is dangerous while driving.
  • Your car is slow to accelerate: Your engine takes in clean air and expels exhaust gasses, which the catalytic converter helps with. If the converter is clogged, your engine can't mix air and fuel efficiently, resulting in poor combustion, power and acceleration.
  • Your car is getting fewer miles to the gallon than usual: Your engine mixes oxygen and fuel using oxygen sensors. A clogged catalytic converter can cause these sensors to misread the oxygen input and inject more fuel than you need. This increased fuel usage further clogs the catalytic converter and requires frequent fill-ups.

What Causes Catalytic Converter Failure Symptoms?

Catalytic converters can break down or perform poorly due to:

  • Oil or coolant leaks: Leaking coolant or oil can contaminate the honeycomb structure inside of a catalytic converter and clog the passages. This issue can cause the engine to misfire or the check engine light to turn on.
  • Age: Catalytic converters have an expected life span of 10 years. If your converter is past its prime, the interior structure can break down, blocking flow and trapping debris.
  • Physical damage: The catalytic converter is underneath the car near the front seat footwells. This position makes it vulnerable to damage if you drive over a curb or hit something in the road. Tailpipe or muffler damage can also ruin the converter from exhaust back pressure and heat buildup.
  • Overheating: The catalytic converter can overheat if it has too much unburned gasoline or the car has a restricted exhaust. Excess heat can cause the interior components to melt.
  • Poor fuel quality: Low-quality gas can have contaminants that won't burn off. This unburned fuel presents a problem because it can become trapped in the catalytic converter.

What to Do When You Notice Bad Catalytic Converter Symptoms

If you notice any of these symptoms in your car, make sure the catalytic converter is causing the problem. Follow these steps to diagnose catalytic converter issues:

  1. Examine the outside of the catalytic converter for signs of damage or discoloration.
  2. Use an OBD-II scanner to read fault codes stored in your car's computer. Codes for catalytic converter problems usually start with P042 or P043.
  3. Run a vacuum test by connecting a vacuum gauge to the vacuum line in the engine. As you increase the RPM, the vacuum should drop, then rise and level off. If the vacuum keeps dropping, it could mean the catalytic converter is clogged.
  4. Test the exhaust temperature using an infrared thermometer in the converter's inlet and outlet. The outlet temperature should be 100 degrees Fahrenheit higher than the inlet temperature.

If your catalytic converter has just started showing these symptoms, try cleaning it to remove buildup. Replace the catalytic converter if the damage is beyond repair. A catalytic converter replacement is a simple repair you can do yourself. If your catalytic converter has failed, consider upgrading your car's exhaust system to increase engine output and emissions quality.

How to Prevent Catalytic Converter Failure

The best way to avoid these bad catalytic converter symptoms is to maintain your vehicle. Keeping your catalytic converter and other car parts in optimal condition can prevent the issues that cause converter failure.

Add these tasks to your car maintenance routine:

  • Change out bad spark plugs: If you've noticed your spark plugs or spark plug wires are fouled, change them right away before they cause further damage.
  • Repair structural damage in your car: Off-road driving, speed bumps, potholes and impacts can damage the catalytic converter by breaking its honeycomb structure or interrupting exhaust flow. If the underside of your car is impacted, repair any damage right away before the catalytic converter is affected.
  • Use fuel additives: Fuel tank additives can prevent contamination in the catalytic converter's honeycomb structure, allowing it to function properly.
  • Inspect your exhaust gas recirculation (EGR) valve: The EGR valve recirculates some exhaust through your engine to use unburned fuel and promote fuel efficiency. If this valve fails, the exhaust is hotter and can melt the interior of your catalytic converter. Inspect your EGR valve to ensure it's intact.

Order a Catalytic Converter Replacement From StockWise Auto

Identifying the signs of a bad catalytic converter is essential to understanding the problem and making the repair or replacement to get your car back on the road. If you need a catalytic converter replacement, check the inventory at StockWise Auto, your trusted source for replacement car parts.

We have converters compatible with many vehicle makes and models at the best price. Our online store has thousands of catalytic converters from reputable manufacturers like MagnaFlowWalker and NissanShop our catalytic converters and other exhaust parts, and place your order today.