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All You Need to Know About a Bad Catalytic Converter

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A catalytic converter (referred to as ‘CAT’) converts the toxic gases a car produces before releasing them into the atmosphere. An integral part of the exhaust system, most cars on the road today have a single one, but many with dual exhausts have two. However, we should know a catalytic converter can go bad over time if there’s no proper maintenance.  

Rather than repairing it, it is best to replace it. But, replacing it is very expensive. So, better to avoid the headache of replacing it with thorough maintenance. But, it is always good to know its problems so that you can give proper care on time!  

So what is a bad catalytic converter? What are the symptoms of a bad catalytic converter? How can you prevent clogged catalytic converters? Here’s all the info you should know!  

What are the issues with a catalytic converter? 

Leaded gas is one possible contaminant that can destroy catalysts. Engine coolant, which may leak into the combustion system due to a damaged cylinder head gasket, and engine oil, are two other contaminants. These fluids can block a cat, stopping exhaust gases from passing through. Less air enters the engine when the exhaust flow is limited, and performance suffers. A bad catalytic converter will be the reason if the engine responds slowly or stops functioning after a while. 

Excess of unburned gas caused by a faulty spark plug or a leaking exhaust valve can overheat them. Also, a defective oxygen sensor can result in overheating. In most cars, you can find it under the vehicle. So, road debris or running over a curb can also damage it.  

Bad Catalytic Converter

What are the symptoms of a bad catalytic converter? 

Have a check if your car has some of these clogged catalytic converter symptoms. Try to repair or do catalytic converter replacement if it shows the following signs.  

Decrease in fuel economy  

The Engine Control Module (ECM) uses data from various sensors inside the engine to optimize the air/fuel mixture in the combustion chambers. A catalytic converter has two sensors – one before and one after it. When there is an internal blockage, the ECM will compensate by injecting more fuel, resulting in a fall in your car’s fuel economy. 

Foul odor from the exhaust 

If you’re driving and suddenly notice the odor of rotten eggs, never doubt the other passengers. It could be the catalytic converter. Why does it happen? Because gasoline contains sulfur, it gets converted to hydrogen sulfide during combustion. If it isn’t functioning correctly, it will convert the sulfide to odorless sulfur dioxide. If not, the hydrogen sulfide will exit the tailpipe before the conversion, causing a foul odor. 

Your car fails the emission test 

The majority of the states require your car to pass an emission test to avoid emitting excessive amounts of pollutants. The certification is valid for 1-3 years and costs around $30-90. A car will be labeled unfit to drive if it doesn’t have the certification. And be ready to pay the penalty if caught driving without the certificate. So, if your car fails the smog test, the chances are high that you have a faulty catalytic converter.

Check engine light turns on  

The ECM uses the data from the two catalytic converter oxygen sensors. The check engine light will illuminate if the ECM senses that the exhaust gases are not catalyzing properly. Be mindful that the appearance of an engine light does not necessarily indicate the problem with it. To ensure, you can take your car to a shop or use an OBDII scanner yourself. 

Engine performance goes down 

Poor acceleration is one of the most common signs of a clogged catalytic converter. It usually happens when it gets too hot for an extended period, resulting in the melting of internal components. Internal blockage happens due to this restricting the exhaust flow. Then get ready to repair or replace the cat. 

Car starts misfiring 

The device failure causes the gas in your engine to heat up to the point of igniting. This ignition causes the misfiring feeling – and it can damage engine components. Do get a car inspection by a reputable service professional when your car starts misfiring.  

The rattling sound coming from under your car 

A rattling sound from your vehicle is always a bad sign. The honeycomb mesh interior can break or collapse when your car has a faulty cat. The car starts making a rattling sound, and the parts vibrate when you start the car.  

When to repair or replace catalytic converter? 

Repairing a car's exhaust

It is always safe to replace a bad catalytic converter. Although cleaning products are on the market, it is better to avoid them. So, the solution lies in replacing the clogged one. Though some states don’t require emissions testing, it violates federal law to remove the cat and replace it with a pipe.  

How to prevent clogged catalytic converter 

The hydrocarbons don’t wholly get burned if you’re driving short distances frequently. It happens because the catalytic converter isn’t getting hot enough. To prevent getting a clogged catalytic converter, drive your car on a highway for around 10-15 minutes from time to time. It will produce enough heat inside the catalytic converter and burn the hydrocarbon deposits efficiently, letting the catalytic converter function well.  

It isn’t cheap to replace a catalytic converter, and it costs around $1,000-2,500 depending on the car you use. You can avoid a bad catalytic converter by doing proper maintenance. Maintain a clean and well-maintained exhaust system to avoid catalytic converter issues.   

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