Overheated Catalytic Converter Symptoms (Causes & Quick Fix)

Overheated Catalytic Converter Symptoms

There are many hidden components of an engine. There is a catalytic converter, which is used to pass fumes in and out of the engine. It is common for this part to get damaged sometimes due to many reasons. In this article, we consider the causes, symptoms, and remedies of an overheated catalytic converter.

What is an Overheated Catalytic Converter?

Before we talk about an overheated catalytic converter, we need to understand what a catalytic converter is and what it does. Catalysts are chemicals that speed up chemical reactions without changing the process.

A catalytic converter is metal equipment screwed/joined/bolted to the bottom of a car. It has both input and output pipes. The input pipes absorb hot gas (fumes) produced by the engine while the output pipes transfer the vapors out.

As fumes from the engine move over the catalyst, a series of chemical reactions are created that change the gasses into less-harmful states.

Some may think that catalytic converters aid in the elimination of air pollution, no that’s not the case. Air pollution is not completely eradicated by catalytic converters, it is only reduced by these converters.

Catalytic converters are at their best performance when they are warm, it usually takes about ten to fifteen minutes of engine idling for it to reach a very warm state. So, expect your car to produce emissions for some minutes when you turn it on.

Now, what is an overheated catalytic converter? Catalytic converters are built to last for more than 10 years. During this time, it is normal for it to get overheated, polluted, clogged, or broken. This leads to a reduced overall performance of the catalytic converter and it is possible it shuts down in the long run.

When you talk about materials that can contaminate catalytic converters, leaded gas is a major culprit. Though rare in the United States, it is highly harmful to converters.

Another is the engine coolant. It is for the engine coolant to leak and get in the combustion system if the cylinder head gasket is damaged. This also applies to engine oil. These materials can affect the catalytic converter and contaminate it or clog it.

In that situation, the exhaust gases will be impeded from moving freely. We all know how the engines of cars work.

They need a constant and sufficient amount of oxygen to operate maximally. When the flow of the exhaust gas is impeded, less oxygen will go into the engine and the overall performance of the car engine will drop significantly.

What causes a catalytic converter to overheat? Surplus volumes of unburned gas as a result of a failing spark plug or damaged exhaust valve can lead to the overheating of a catalytic converter. The presence of a faulty oxygen sensor can also make a catalytic converter overheat.

To elaborate, some fuel injectors can leak leading to unburned fuel burning inside the converter. The remaining fuel will melt and the substrate will get overheated. Excess oxygen in a combustion chamber can lead to misfiring. This is commonly known as lean burn.

Now, that misfiring will lead to the accumulation or piling of hydrocarbon inside the catalytic converter; the accumulation will block the converter and lead to overheating.

As for a failing oxygen sensor, the catalytic converter in your car’s engine is connected with oxygen sensors. Oxygen sensors are basically used to measure the mixture of fuel and pure air.

When the oxygen sensor becomes faulty, it cannot perform its role and the mixture gets imbalanced. If that happens and it is too concentrated, it can result in the overheating of the catalytic converter.

How do you know an overheated catalytic converter? The normal temperature of a catalytic converter is between 1200- and 1600-degrees Fahrenheit. When it is overheated, the color changes and it becomes very red, a noticeable red color.

If you measure the temperature of an overheated catalytic converter, it will be around 2000 degrees Fahrenheit.

Overheated Catalytic Converter Symptoms

Catalytic converters can be very expensive to replace or fix when damaged so it is wise to know when your catalytic converter is about to overheat.

How can you identify an overheated catalytic converter?

  • The easiest way to identify an overheated catalytic converter is with the smell; it produces a rotten egg (sulfur) smell.

Other overheated catalytic converter symptoms are:

1. Check Engine Light

The check engine light is the common way to know when a part of your engine is faulty or damaged. When you see the light, it does not necessarily mean that the catalytic converter might be the cause but you should check further.

You can make use of an OBD scanner to know the root cause of the check engine light. If it is an overheated catalytic converter, you will observe the P0420 code.

2. Rotten Egg Smell

An overheated catalytic converter produces a sulfur smell. This smells just like a rotten egg. It is highly unpleasant and difficult to ignore.

If the converter is blocked or clogged, the airflow of exhaust gases is impeded and the mixture of pure air and fuel becomes rich (unburnt fuel due to excess fuel).

The rotten egg smell is caused by the combustion of the excess air and fuel mixture. When you perceive this odor, you should check your catalytic converter.

3. Delayed Acceleration

When your catalytic converter is overheating, you will notice a lag in acceleration. You should check other parts of the engine as well.

Check the oxygen sensors, the filters, the spark plugs, etc. and if they are all working fine, you need to check the catalytic converter as well.

There are other symptoms of an overheated catalytic converter including rattling noises, misfiring of the engine, low or high fuel consumption, sluggish engine performance, and excessive heat under the vehicle.

Whenever you observe any of these things, you should check the catalytic converter.

What You Should Do if your Catalytic Converter is Overheating

An overheating catalytic converter needs to be fixed or replaced as soon as possible. Fixes are most used as temporary measures, if the catalytic converter is damaged or clogged heavily, it is best to replace it.

How do you fix an overheating catalytic converter? You need some tools such as a jack, a hose, a set of sockets and a cleaning agent. You can do this with someone else to make things easy.

  • Firstly, check out the muffler to make sure it is physically intact. If it needs replacement, do it.
  • Then, drive your car around for a while to warm up the engine. This will make the converter get hot. It is possible that what it needs is a warm-up to get it working perfectly.
  • After that, you need to ramp up the RPMs.
  • Add a cleaning additive afterward to dislocate dirt and unwanted particles inside the converter.
  • Clean the catalytic converter thoroughly to be sure it’s free from dirt.

If you need to replace it, you can get a brand new catalytic converter for between $400 and $2500.

Final Thoughts

The catalytic converter is more important than many people think. You should not ignore it when it needs to be replaced or fixed. Also, follow the recommended maintenance schedule of your vehicle to ensure you do not have a damaged catalytic converter.