Clogged Exhaust Symptoms – Causes and How To Fix It

Clogged exhaust symptoms identification is crucial in knowing the exact cause of the problem. The reason is that different factors lead to a blocked exhaust system.

Clogged Exhaust Symptoms

Thus, using a wrong fix won’t save the day and may only complicate matters. This article will discuss the common signs of a congested tailpipe system, uncover the causes and suggest ways to solve them.

What Are the Causes of a Clogged Exhaust System?

The causes of a clogged exhaust system include debris outside the vehicle, a blocked catalytic converter and a dirty muffler. A buildup of rust in the system can block the flow of gasses, though it is not common. Usually, cleaning the exhaust system should solve the problem.

Debris from Outside the Car

The exhaust system’s function is to get harmful gasses out of the vehicle through the tailpipe. Though that is a good thing, the tailpipe can be a source through which debris can get into the exhaust system. Although this is rare, small objects like stones, sticks, grass, and leaves can enter the exhaust system through the tailpipe and cause problems. Unscrupulous persons could also deliberately drop objects in the tailpipe to cause havoc.

A clogged exhaust pipe can lead to engine power loss as it doesn’t get enough air for complete combustion. A clogged exhaust system means that the exhaust gasses will remain in the combustion chamber with no room to escape. Thus, new air can’t make its way into the chamber for proper combustion, affecting engine power output. This leads to low acceleration as the vehicle struggles to match the pressure you exert on the accelerator pedal.

At first, you might think the poor acceleration results from low fuel, but that assumption will disappear after you top up the gas, and the problem persists. You might experience other signs, such as jerking and stalling. Sometimes the vehicle will struggle to go uphill, and depending on the slope, it may come rolling down in reverse. The vehicle may struggle to idle and turn off when you’re in traffic due to low engine power.

A Clogged Catalytic Converter

Substances from the engine are the most common cause of a clogged catalytic converter. Due to the converter’s work, which is to transform harmful gasses into less harmful substances, it easily gets clogged. Sometimes a leakage from the engine (coolant leaks or oil) can gather on the surface of the cat converter. 

Causes of a Clogged Exhaust System

These substances get burned due to the extreme heat inside the cat converter, forming a thick soot that clogs the air passages on the converter’s honeycomb.

When that happens, the exhaust gasses can’t go through the honeycomb, increasing backpressure. Back Pressure then forces the gasses back into the combustion chamber, resulting in engine overheating and loss of power. A bad catalytic converter can also cause engine damage if it’s not checked early.

Unburned Fuel Entering the Cat Converter

Normally, fuel has to be burned in the combustion chamber to produce power for the vehicle. However, some fuel can escape due to faulty spark plugs, worn-out pistons, damaged ignition, etc. When that happens, the fuel ends up in the exhaust system, where it is combusted by the heat in the converter. This can cause the melting of the converter as the heat produced by the burning fuel may be above the converter’s threshold, illuminating the check engine light.

When this happens, you might begin to experience high fuel consumption, especially when the cat converters are blocked. Catalytic converters improve fuel efficiency by allowing enough airflow to mix with the fuel for proper combustion. A blocked cat converter will cause the build-up of exhaust gasses. These gasses will block proper airflow, leading to incomplete combustion, carbon monoxide emissions and reduced engine performance.

Incomplete combustion robs the vehicle of the energy it needs to run, forcing the engine to work harder to compensate for the power loss. Thus, the engine consumes more gas to get the vehicle going, increasing the mileage. This load leads to the production of more exhaust gasses, compounding the cat converter’s problems. The trapped exhaust gasses can also damage the engine if you don’t take appropriate steps to rectify the situation.

Faulty Oxygen Sensors

Another cause of a clogged exhaust system is a faulty oxygen sensor. The sensors inform the engine control unit (ECU) whether there’s enough oxygen for combustion. The ECU uses this information to adjust the flow of oxygen so that the car can run well. If the oxygen sends faulty readings, the ECU may allow too much or too little oxygen.

If the oxygen is too much, it’ll produce rich combustion, which will create excess heat, causing the converter to melt. However, too little oxygen leads to lean combustion, which produces hydrocarbons that the cat converter will struggle to convert to safer gasses. Either way, the converter gets damaged and results in engine performance issues.

A Dirty Muffler

A muffler dampens the noise that comes from the engine and is connected to the cat converter. Exhaust fumes pass through the muffler, occasionally clogging it. A clogged muffler results in back pressure that sends the exhaust gasses back to the combustion chamber. Muffler failure symptoms include engine overheating and misfiring.

When the gasses can’t get a way to escape, they build up and eventually block the converter. When this happens, the temperature of the gasses rises due to the pressure buildup in the converter. Over time, the gasses become very hot to the point of ignition, causing engine misfires.

On the other hand, the exhaust gasses build up in the combustion chamber, preventing fresh air from coming through. Thus, the engine begins to run lean as there’s not enough air to blend with the fuel for proper combustion, causing engine misfires. Engine misfires can cause rough idling, stalled acceleration, and jerking.

How To Fix a Clogged Exhaust System

To fix a clogged exhaust system, you’ll need to determine the component causing the blockade problem. The culprits, usually, are either the catalytic converter, the muffler or can even be both. Once you’ve determined the root of the problem, you can go ahead and fix the issue. 

If the problem is from the catalytic converter, then you must perform a deep clean to clear all debris in the system. 

How To Clean a Catalytic Converter at Home

To clean a catalytic converter at home, first ensure your car’s fuel level is right because you’ll need about 15 liters of gas. Also, get a catalytic cleaner and check your car manual to ensure you use the exact fuel-to-cleaner ratio. Now, pour the catalytic cleaner into the fuel. 

Make sure you adhere strictly to the guidelines on the cleaner’s container and the car’s manual. Then drive the car around for about 30 minutes at over 2500 rpm for the cleaner to do a thorough job.

Fix a Clogged Exhaust System

After the time has elapsed, check for signs of a clogged converter, which we’ve discussed above. If these signs are gone, your problems are solved. Note that this method only works when the converter is slightly clogged. A heavily blocked converter requires a lot more work, which is why the catalytic converter replacement cost is quite high.

This method involves removing the catalytic converter and cleaning it. Once the converter is off, use a pressure washer set to low to wash the inside of the device. Pour hot water into a large container, add a degreaser and immerse the converter into it. Clean the converter again with the pressure washer and leave it to dry before reinstalling it on the car.

Cleaning a Clogged Muffler at Home

First, you’ll need to remove the muffler, which can be tricky. We advise you to consult your car’s manual for directions on how to remove the device. Now, fill a large container with a degreaser, put in the muffler and leave it overnight. Next, remove the muffler and rinse the degreaser with water and leave it out to dry.

Remember to replace the muffler and fix all the screws you removed. If you need any help in refixing the muffler, consult your car’s manual on how to fix a clogged muffler or catalytic converter. Otherwise, you can take the vehicle to a professional to do a thorough job.

Frequently Asked Questions

What Are the Symptoms of a Clogged Exhaust System?

The symptoms of a clogged exhaust system include high fuel consumption, loss of engine power, a burning smell and fuel odors. A failed engine start, misfire and strange noises from the car’s tailpipe are all signs showing that the exhaust system needs repair.

What Is the Source of a Burning Smell in a Clogged Exhaust System?

The source of a burning smell in a clogged exhaust system is hot gasses that burn or melt anything around it, including wires and plastics. The odor may come from the engine or the exhaust system. The engine produces hydrogen sulfide, which the catalytic converter converts to odorless sulfur dioxide

Thus, if the converter is broken, it will allow the hydrogen sulfide gas to pass through the exhaust system unconverted. You’ll then begin to perceive a rotten egg smell while driving because that’s the smell of hydrogen sulfide, which is one of the symptoms of a clogged catalytic converter. So, whenever that happens, know that your exhaust system needs repair.

Clogged Muffler of a Car

Can a Clogged Exhaust Cause Intake Manifold Gasket Symptoms?

Yes, a clogged exhaust can indeed lead to intake manifold gasket symptoms spotted. When the exhaust system becomes obstructed, it can cause pressure to build up in the intake manifold, resulting in symptoms such as rough idling, decreased engine performance, and potential coolant leaks. Regular maintenance and addressing exhaust issues promptly can help prevent these gasket symptoms.


A clogged exhaust manifold usually throws up several signs to caution you before the engine gets damaged.

Here is a recap of the signs, causes and solutions to the problem:

  • The symptoms of a clogged exhaust system include high fuel consumption, loss of engine power, sulfuric smell, and engine misfires.
  • These symptoms are caused by debris outside the vehicle, a clogged cat converter, unburned fuel in the converter and a faulty oxygen sensor.
  • A blocked muffler can prevent the exhaust gasses from escaping through the tailpipe and redirect them to the combustion chamber, causing back pressure.
  • An increase in back pressure can damage the engine, as the combustion chamber doesn’t get enough ‘clean’ air to power the engine.
  • The lack of engine power will make the car struggle to accelerate, climb up a hill, jerk or go off whenever it idles.

To solve the problem, you must clean the catalytic converter and the muffler with cleaning agents such as degreasers to eliminate all obstructions. You can enlist the help of a professional to do a thorough job while keeping the devices intact.

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