In this era, when all governing bodies and carmakers are hell-bent on curbing vehicular emissions, the significance of catalytic converters has risen higher than ever. A crucial part of a vehicle’s exhaust system, a catalytic converter reduces hydrocarbons and pollutants produced as by-products during the combustion of the fuel within the engine.

However, like any other vehicular component, catalytic converters are also prone to malfunctioning under certain conditions. Failing to detect symptoms of a problematic catalytic converter like sluggish engine performance, warning signals, and poor emissions, and repair issues can cause significant damage to the powertrain and exhaust system. In this article, we will explain the various symptoms that indicate the improper functioning of a catalytic converter and the reasons behind them.

What Is a Catalytic Converter?

Catalytic converters emerged as a solution to curb vehicular air pollution in the 1970s when car manufacturers and environmentalists decided to reduce vehicular emissions substantially.

• The fuel combustion within a vehicle engine releases harmful by-products like carbon monoxide, nitrogen dioxide, sulfur dioxide, hydrocarbons, and lead.
• Attached to a vehicle’s exhaust system, a catalytic converter is positioned between the engine and the exhaust muffler.
• It is a metal canister with a honeycomb mesh-like structure coated with precious elements like platinum, rhodium, and palladium.
• These metals serve as catalysts to filter out toxic gases and convert them into safer by-products, including NOx gases into nitrogen gas, and carbon monoxide and hydrocarbons into carbon dioxide and water.
• The catalytic converters can heat up to 800 degrees Fahrenheit for these chemical reactions to take place.

Symptoms of a Bad Catalytic Converter

A bad catalytic converter doesn’t just hurt your car’s health, but also puts you at risk of flunking an emission test. There are a few signs that do tell you whether the catalytic converter of your vehicle is in good condition or not, all of which are as follows:

Poor Acceleration

When the  catalytic converter gets clogged with harmful by-products from burned fuel, it chokes the airflow your engine needs to mix air and fuel properly.. This restricted airflow can lead to poor combustion of fuel, which can eventually result in poor acceleration. ‘

A vehicle engine can also suffer from poor acceleration if any of the internal components of the catalytic converter get broken.

Engine Misfiring

Another result of a catalytic converter going wrong is the irregular combustion of fuel within the firing cylinders, which can lead to engine misfiring. When that happens, your car might start jerking out of nowhere, stall unexpectedly, or even refuse to start altogether.

Bad Odour Around Exhaust Tips

If you detect a rotten egg-like smell around the exhaust tip(s), it means that the catalytic converter is not absorbing hydrogen sulfide, one of the many harmful gases emitted after air-fuel combustion. The unpleasant smell can even create discomfort while driving, signaling that the extent of damage is high.

Reduced Fuel Economy

A drop in fuel efficiency can be due to various reasons, including poor fuel quality, wearing out of the internal components, and a damaged catalytic converter. If the drop in fuel efficiency is in the range of 8-15 percent, it can be a result of catalytic converters not doing their job effectively. However, in this case, a faulty fuel pump and clogged fuel filter can also be a reason, so it is advisable to check these components while diagnosing.

Check Engine Light

The ‘check engine light’ is a warning signal in your vehicle that lights up when the electronic control module detects potential failure of any system linked to its powertrain. A clogged catalytic converter or abnormal fluctuations in its operating temperatures can also trigger this warning light.

Rattling Sounds Around the Exhaust System

The breaking up of any internal component of the catalytic converter can result in rattling noises around the vehicle’s exhaust system. In this case, the rattling effect is less evident during idle and more prominent whenever you accelerate. 

Emission of Blue Thick Dark Smoke

Another clear visual indication of a faulty catalytic converter is the emission of blue smoke or thick dark smoke from the exhaust tip(s). This symptom can be due to sulfur accumulation within the catalytic converter. If you ignore this issue, the components might wear more rapidly.

Engine Overheating

The reduced airflow due to clogging of the catalytic converter with impurities also results in heat build-up within the engine. If this increased heat gets trapped within the cylinders of the engine, it can overheat the whole block, leading to severe damage to the internal walls of the engine and, of course, to hefty damages.

Primary Reasons Behind Malfunctioning Of a Catalytic Converter

There are several reasons for the improper functioning of a catalytic converter, with most of them leading to the accumulation of soot within it, creating a blockage. Following are all of those reasons:

High Mileage

With time and continuous usage, the chemical structure of the catalytic converter deteriorates gradually. The worn-out particles or chemical substances in the catalytic converter can block the airflow and harmful gases. Due to this, the particulate matter accumulates within the catalytic converter.

Unburnt Fuel in Exhaust System

The improper combustion of air-fuel mixture due to worn-out spark plugs or damaged engine valves can lead to unburned fuel emitted through the exhaust port. This unburnt fuel can lead to carbon deposits or soot in the catalytic converter, eventually leading to blockage and improper functionality.

External Impact Due to Collision

A catalytic converter can also get damaged from external impacts. Hitting a pothole too hard, scraping over a speed bump, getting struck by road debris, or being involved in a crash can all crack or dent the converter. Such a physical impact on the surface of the catalytic converter can cause internal components to break, setting off a chain of problems.

Poor Quality Fuel

If the fuel fed to your vehicle has a high amount of contaminants, they can clog the catalytic converter even after the combustion process within the engine.

Rich fuel mixture (air or fuel leaks)

If your vehicle runs on a richer air-fuel mixture for combustion, the improper combustion process can lead to more fuel accumulation in the catalytic converter. A faulty fuel injection system might lead to such circumstances, where the engine is fed with more fuel than required. The residual fuel then flows into catalytic converters, creating a blockage.

Oil or Coolant Leaks

In addition to fuel, the oil or coolant leakage into the catalytic converters due to a possible crack in the engine’s head gasket or intake manifold can also create blockage in a catalytic converter. This can alert the electrical control module, which sends a warning by triggering the ‘check engine light’.

How to Diagnose a Bad Catalytic Converter

Fixing a faulty catalytic converter is generally tricky and requires expertise and equipment, which is possible only at an authorized service center. Following is a step-by-step procedure for diagnosing a catalytic converter:

Step 1: Note the symptom

We have already mentioned various symptoms of a faulty catalytic converter above. If you see or sense any of these symptoms, it is time to visit a service center.

Step 2: Scan the vehicle’s computer

Like many of the systems in a modern vehicle, the functionality of a catalytic converter is also electronically controlled. A fault in the catalytic converter can be detected using an OBD-II scanner, through which you can obtain the fault codes to operate.

Step 3: Vacuum test

If your vehicle’s catalytic converter is clogged with impurities, a vacuum test can help you know the truth. After connecting a vacuum gauge to the engine’s vacuum line, increase the gauge’s RPM slowly. Ideally, the vacuum should rise and level off after an initial drop, but if the vacuum is dropping continuously, it means that the catalytic converter is clogged.

The Expenses Involved: Is Replacement Better or Repair?

One of the most complex parts of a vehicle, the catalytic converter, is different in size and cost depending on the type of vehicle.

Usually, catalytic converters begin at around $1,000 for entry-level compact cars, cost around $2,200-$2,600 for mid-size cars and SUVs, and can even cost more than $3,000 for luxury vehicles. 

Several factors determine the costs involved in replacing catalytic converters, such as the age of the vehicle and the market costs of components used in it. For example, rhodium, one of the most expensive elements costing $20,000 per ounce, is a key element of an entire structure of catalytic converters.

Usually, a replacement is the most obvious choice in case a catalytic converter faces any of the issues mentioned above. If the damage is minor, fixing a catalytic converter can be considered, which can cost as little as $300. But if the damages are larger, repairing a catalytic converter can be highly complex and expensive, to the extent that a replacement is considered an easier and relatively affordable thing to do.

Conclusion: Significance of a Healthy Catalytic Converter

Driving with a faulty catalytic converter is not entirely impossible, but doing so over a long period will only harm your vehicle and the environment. There will be a performance drop in your vehicle, and your powertrain’s life will deteriorate. It can be best explained as a slow death, where the components of the engine will damage slowly due to accumulated byproducts of combustion or unburnt fuel.  

There are only two ways to deal with this concern – preventive measures and sudden action. While you can prevent this situation as much as possible with proper vehicle maintenance, you should also rectify or replace a faulty catalytic converter as soon as possible once it starts indicating problems.

FAQs:

Q1. How do you know if your catalytic converter is going bad?

There are a few signals indicating a fault in a catalytic converter, such as sluggish performance, drop in acceleration or fuel efficiency, foul smell near the exhaust port, and dark or bluish smoke.

Q2. Can a catalytic converter affect acceleration?

Yes, a faulty catalytic converter can result in drop in acceleration, which is possible due to clogging of harmful by-products of combustion within it.

Q3. Can you drive with a bad catalytic converter?

While one can drive a car with a bad catalytic converter, doing so for a longer time can result in gradual deterioration in the performance and condition of its engine.

Q4. Can you unclog a catalytic converter?

Cleaning a catalytic converter is possible with cleaners in case of soot or hydrocarbon clogging. However, the overall process is complex and can be expensive. Also, replacement is considered a more optimal solution in case of serious damages to the converter.

Q5. Will a car run without a catalytic converter?

Modern car engines are designed to be used with catalytic converters, which help carmakers achieve more stringent emission norms and make the engines run cleaner and more fuel-efficient. Running a car without a catalytic converter can significantly drop fuel efficiency and performance while making it more polluting.