Top Symptoms of a Bad Catalytic Converter & How to Fix ItSymptoms of a Bad Catalytic Converter
A catalytic converter is an exhaust emission control device that reduces the amount of toxic gases and pollutants emitted by your car. Over time, the catalytic converter may become clogged, leading to restricted exhaust flow, a check engine light, engine misfires, and reduced power. A bad catalytic converter will cause several symptoms that are hard to miss.
When this part becomes clogged, exhaust flow is restricted, reducing the amount of air entering the engine. This leads to engine misfires, check engine light flashing, poor acceleration, engine problems, and the check engine light coming on.
Symptoms of a Bad Catalytic Converter
The most common symptoms of a bad catalytic converter are:
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- Backfiring.
- Poor acceleration.
- Check engine light is on or flashing.
- Sluggish engine performance.
- Dark exhaust smoke.
- Excessive heating coming from under the vehicle.
- Engine overheating.
- Rotten eggs smell from the exhaust..
- Exhaust smoke.
- Excessive exhaust temperature.
- Decreased engine performance.
- Failed emission or smog test.
- In some cases, the car won’t start.
- Fault codes preset.
Some of these symptoms can be caused by other related issues, such as bad spark plugs, an ignition coil, an air filter, a fuel filter, or a fuel pump. We recommend properly diagnosing your car using an OBD-II scanner before replacing the catalytic converter.
How to Test for a Bad Catalytic Converter
A catalytic converter does not need to be removed to be tested. A red glowing catalytic converter is a common symptom pointing to the componend being bad. An experienced auto mechanic can quickly spot a bad catalytic converter by its symptoms. It is highly recommended to perform one or more tests to verify that this part is faulty before replacement.
Here are a few tests that can be performed to test a catalytic converter:
- Temperature test – Let the car warm up to operating temperature. While the engine is still running, lift the vehicle. Use an infrared thermometer to measure the inlet temperature of the converter. Then measure the temperature at the converter’s outlet, which feeds into the exhaust pipe. Because the conversion process produces heat, the outlet pipe’s temperature should be higher than the inlet temperature. If the opposite is true, the converter is clogged or broken.
- Sound test – You can also tell if it is broken by simply hitting it with a mallet. Do this when the engine is off and the converter is cold. Crawl under the car, find the converter, and hit it with your hand. If you hear something rattling inside, the honeycomb inside is broken, and you need a new one.
- Exhaust backpressure test. This is not a test that you can do yourself. An exhaust back pressure test will need to be performed by an auto mechanic or a muffler shop. The mechanic will drill a small hole in the catalytic converter’s front and attach a small probe to a gauge. The engine is started, and the exhaust back pressure is measured with a gauge. If there is excessive pressure buildup, it indicates a clogged catalytic converter restricting exhaust gases.
What does a bad catalytic converter sound like?
It’s not easy to identify a bad catalytic converter by sound because it will not make any unusual sounds, even when it is clogged. Instead, pay attention to the car not idling properly or the engine running rough. This is because the exhaust gases are not passing through properly and are not making it out of the tailpipe, which causes backpressure, and the engine does not run properly. You may hear broken pieces rattling inside the converter when you hit it with a mallet.
What does a bad catalytic converter look like?
One way to tell if the catalytic converter is bad is to inspect it after the vehicle has been running for at least 15 minutes.
If the catalytic converter is bad, it will glow red. This signifies that either the catalytic converter is clogged or fuel is being burned inside, typically due to a bad spark plug or ignition coil.
Can you drive a car with a bad catalytic converter?
While the engine may still run, we wouldn’t recommend driving a vehicle with a bad catalytic converter. If it is bad, the car will not run properly, leading to more damage to the engine if not fixed right away.
How do you unclog a catalytic converter?
It is possible to clean a blocked converter. You will need a bottle of catalytic converter cleaner, which is available at auto parts stores or online. Pour the additive into your fuel tank. We recommend doing this when your gas tank is full so there is an even mix of cleaner and fuel.
NOTE: This will only work on a partially clogged converter. A completely blocked converter should be replaced immediately.
How long does a catalytic converter last?
Most catalytic converters last about 8 to 10 years. However, we have seen a few fail as early as five years, and some last up to 20 years.
If your catalytic converter only lasts a couple of years, this can be due to an engine problem or a poorly maintained vehicle. When the catalytic converter fails, it will get clogged, leading to poor acceleration, mostly uphill, a check engine light coming on, and even the engine overheating or shutting down.
How to maintain a catalytic converter?
Performing basic tune-ups —such as changing the oil, spark plugs, and air filters on time —will help your catalytic converter last longer. Keep your engine running at its best to make a catalytic converter last longer.
How much does it cost to replace the catalytic converter?
Changing the catalytic converter is an expensive repair. The cost to replace it can range from as low as $800 to $3000 for a direct fitment (OEM) catalytic converter.
A cheaper alternative is to visit a muffler shop and install a universal catalytic converter. These range between $300 and $500. Instead of replacing the whole catalytic converter and the pipes, a muffler shop will cut out the catalytic converter and weld a universal catalytic converter.
We have had universal catalytic converters installed on many vehicles. They work just as well as their OEM counterparts for a fraction of the cost. The check engine light can be reset, and you can now pass your emission test.
Why does a catalytic converter fail?
One of the most common problems that leads to the premature failure of the catalytic converter is worn spark plugs. When the spark plugs are not replaced at the recommended intervals, they wear out, which leads to fuel not completely getting burned in the engine. Fuel exits the engine with exhaust gases but gets burned in the catalytic converter, leading to its premature failure.
How many catalytic converters does a car have?
Cars with four-cylinder engines have only one catalytic converter. Cars with six, eight, ten, or twelve cylinders typically have two.
Troubleshooting with YOUCANIC Full-System Scanner
The YOUCANIC Full System Scanner can troubleshoot many problems in your vehicle, including catalytic converter issues. This powerful device can read and clear fault codes from all the systems, perform bi-directional tests, perform maintenance and repair resets, and much more.
We hope you find the Symptoms of a Bad Catalytic Converter guide helpful. Check these troubleshooting and repair guides for more help on your vehicle.
