A catalytic converter, often referred to as a ‘CAT,’ is designed to convert the toxic gases produced by a car before they are released into the atmosphere. It is a crucial component of the exhaust system. Most cars on the road today have a single catalytic converter, although vehicles with dual exhaust systems may have two. However, over time, a catalytic converter can deteriorate if proper maintenance is not carried out.
It is usually better to replace it than to repair it. However, replacement can be very expensive. To avoid the hassle of replacing it, focus on regular maintenance. It is also important to know its problems so you can provide proper care when needed.
So, what is a bad catalytic converter? What are the symptoms of one? How can you prevent them from clogging? Here’s all the info you should know!
What problems can happen with a catalytic converter?
Leaded gas can harm catalytic converters. Other contaminants include engine coolant, which may leak into the combustion system if the cylinder head gasket is damaged, and engine oil. These fluids can block the converter, preventing exhaust gases from flowing through. When exhaust flow is limited, less air enters the engine, and performance decreases. In turn, this can make the engine slow to respond or cause it to stop working entirely.
Excess unburned gas caused by a faulty spark plug or a leaking exhaust valve can overheat them. A defective oxygen sensor can also 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.
What are the signs of a failing catalytic converter?
Check if your car has any signs of a clogged CAT. If you notice these symptoms, consider repairing or replacing the catalytic converter.
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 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.
The check engine light turns on
The ECM uses the data from the two catalytic converter oxygen sensors. If the ECM senses that the exhaust gases are not being catalyzed properly, the check engine light will illuminate. Be mindful that the appearance of an engine light does not necessarily indicate a problem. 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 CAT. 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.
Your car starts misfiring
The device failure causes the gas in your engine to heat up to the point of ignition. This ignition causes a misfiring feeling, and it can damage engine components. When your car starts misfiring, get it inspected by a reputable service professional.
The rattling sound coming from under your car
A rattling sound from your vehicle is a warning sign. If your car’s CAT is faulty, the honeycomb mesh inside can break or collapse. When you start the car, you may hear a rattling noise as the parts vibrate.
What causes catalytic converters to fail?
The possible causes for a bad catalytic converter are the following.
- Incorrect fuel mixture
- Defective spark plugs
- Improper timing
- A broken oxygen sensor
- Faulty fuel injector
- Sticking float
- Damaged check valve
When to repair or replace a catalytic converter
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 a 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, which costs around $1,000-2,500, depending on the car you use. Proper maintenance can prevent a bad catalytic converter. Maintain a clean and well-maintained exhaust system to avoid catalytic converter issues.
Can you drive with a bad catalytic converter?
The truth is that the majority of the issues related to catalytic converters don’t impact your car’s functioning. We don’t encourage driving with a bad catalytic converter if you’re dealing with a fully plugged one. Drive your car to a technician immediately if you happen to see smoke coming from your car.
At what mileage do catalytic converters go bad?
The job of a catalytic converter is to eliminate your car’s harmful emissions, and it does eliminate 90% of the emissions. If your car is maintained in the best condition, the CAT can function for more than 100,000 miles. Sometimes, it may function as long as the car is driven.
Can you fix a bad catalytic converter?
You can likely fix the problem if you identify the issues early on. However, you should replace the item if it shows signs of discoloration, rattling, warping, or smells like sulfur.
Common Queries
How does a bad catalytic converter sound?
They would make a loud rattling sound or a sound that implies the engine isn’t functioning smoothly as it usually does. This indicates that there’s excess sulfur in the exhaust system, which can make it ineffective.
Should I replace my catalytic converter or get a new car?
If the cost of the new catalytic converter is more than the price of the car, then it is best to invest in a new car. However, if the replacement cost is cheap, then it is better to invest in buying a new converter than a new car.
Can a bad catalytic converter ruin your engine?
Driving with a bad catalytic converter or a rattling one isn’t that dangerous. But it will increase the harmful emissions from your car, implying you’ll get exposed to several pollutants.
What happens if I don’t fix my catalytic converter?
Though driving with a bad catalytic converter isn’t that dangerous, you must get the issues fixed without much delay. If not, it’ll cause problems with your car’s powerplant, eventually leading to strange noises, foul odors, and engine failure.
Gerard Stevens is an experienced writer specializing in travel and car ownership in the U.S. With over five years in this field, he strives to simplify travel and driving for his readers. Gerard offers valuable guidance on various topics, including car and travel guides, helping his audience feel more confident in navigating these challenges.
