Summary
- A catalytic converter is a device that burns the unburned hydrocarbons before they leave the vehicle’s exhaust system.
- When the catalytic converter goes bad, the engine performs sluggishly and sometimes shuts down entirely.
- Sometimes, when the vehicle’s engine faces issues like incorrect air/fuel mixture, bad spark plugs, inaccurate engine timing, bad oxygen sensor, and bad valve cover gasket or piston rings, it damages the catalytic converter.
- You can identify a bad catalytic converter by noticing symptoms like checking the engine light on, rotten egg smell, overheating, and losing power and acceleration.
- It can also be identified using devices like OBD, and OTC exhausts back pressure gauges.
- Most issues with catalytic converters are usually fixed by cleaning or replacing the converter.
What is a Catalytic Converter?
It is made from a material that is heat resistant and has a honeycomb structure inside it. Said structure has a coating of some metals such as Platinum, Palladium, and Rhodium. These metals help the catalytic converter break down the hydrocarbons. A catalytic converter is a costly device owing to the metals used inside.

How Long Does A Catalytic Converter Last?
The answer to the question of how long a catalytic converter lasts is simple. Catalytic converters are made of materials that can last as long as a vehicle does if taken care of properly. However, the real problem is that their care is connected to the care of other parts of the car. When some car components fail to work correctly, they cause the engine to burn coolant or oil. This burnt oil or coolant reaches the catalytic converter and clogs it. Before moving toward the factors that cause the catalytic converter to go wrong, let’s look at some signs of a bad catalytic converter.

Signs of a Bad Catalytic Converter
If a catalytic converter is clogged and has gone bad, your car may show some of the following signs.
Overheating
When gases get trapped inside the engine due to the non-availability of an exit, pressure starts to build up. Due to the said pressure, you will observe that your car is overheating.
Loss of Power and Speed
You may also witness that your car has lost its power or cannot pass a certain level of speed. It is because the gases trapped inside the engine keep gathering; they pressure the engine. In such circumstances, the engine fails to perform, and your car fails to go above a certain level of speed.
Check Engine Light
If your car suffers from a bad catalytic converter, you may see your car’s check engine light on. This is because your car’s oxygen sensor gauges when enough gasses are emitted through the exhaust. If the oxygen sensor senses that gasses meant to be exhausted outside are trapped inside the engine, it signals the car’s computer that something is going bad.
Rotten Egg Smell
As a result of the engine’s internal combustion, many gasses are generated. Hydrogen sulfide is one of them and smells like a rotten egg. However, a working catalytic converter converts the hydrogen sulfide into sulfur dioxide, which is odorless.
Rattling Noise
When the pressure of gasses increases due to the clogging of the honeycomb, pressure and heat rise. Due to such pressure and heat, some parts of the honeycomb split up and started moving freely inside the catalytic converter. Due to the free movement of a separated part, we may hear a rattling noise from under the car while braking or accelerating.
Bad Fuel Economy
When your catalytic converter is clogged and causes an accumulation of gases, the engine comes under pressure and fails to perform accurately. When the engine loses its acceleration due to the pressure of gases, you put more pressure on the acceleration pedal. In such a situation, the engine consumes more fuel and tries to meet your demand, i.e., increasing the speed. However, clogging of the catalytic converter still prevents it from doing so. Therefore, you may notice a bad fuel economy.

Causes of a Bad Catalytic Converter
An internal combustion engine is made up of many parts. Therefore, the failure of a single component may cause the engine to work improperly. As has already been discussed, a catalytic converter can last the lifespan of your car. However, when an engine suffers from an issue, it damages the catalytic converter. Following are some of the significant problems of the engine that damage the vehicle’s performance and catalytic converter.
- Incorrect air/fuel mixture;
- Bad spark plugs;
- Inaccurate engine timing;
- Bad oxygen sensor;
- Unburned fuel coming from the combustion chamber;
- Bad valve cover gasket and seals;
- Worn-out piston rings;
- Catalytic converter hit by any external object.
Diagnostics
You can get your car to a mechanic for running diagnostics, but if you want to save money and do it yourself, here are some tests.
OTC Exhausts Back Pressure Gauge
If you want to test if your car’s catalytic converter is working correctly, you can use an OTC exhausts back pressure gauge. It is an excellent little gauge that can be bought for just a couple of dollars. When the catalytic converter goes terribly, immense pressure is built inside the pipe that takes the exhausting gases from the engine to the catalytic converter.
OTC exhaust back pressure gauge can be easily attached to the engine by taking out the oxygen sensor and putting it in. If the pressure is a pound and a half, it’s normal; however, anything over three pounds shows inside the catalytic converter is clogged up. Moreover, pressure after the catalytic converter must also be checked as sometimes, the muffler is clogged up.
Using OBD Scanner
If your car suffers from a bad catalytic converter, you can check it with a scanner called OBD. It is a beneficial gadget not only for automobile mechanics but also for drivers. It is very cheap and ranges from $40 to $400. If the scanner shows any one or some of the following codes, it means that your car’s catalytic converter is having some trouble.
P0420
P0427
P0434
P0421
P0428
P0435
P0422
P0429
P0436
P0423
P0430
P0437
P0424
P0431
P0438
P0425
P0432
P0439
P0426
P0433
Fix Bad Catalytic Converter
It does not mean that a catalytic converter that has gone bad must be revived. Sometimes it is possible to fix your bad catalytic converter. For example, in some cases, the catalytic converter has just lost its efficiency and can be restored by cleaning.

Many cleaners are available in the market; however, you can also use lacquer thinner for this purpose. First, put a gallon of lacquer thinner in the half-full gas tank. Then, run the engine at about 2500 RPMs for about 30 minutes to run the cleaner through. It can burn the impurities out of the catalytic converter and make it work again.