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Can an Exhaust Leak Cause a Misfire? (All You Need to Know)

If you begin to notice your car engine misfiring, do not ignore it. Because finding the problem and solution for the misfire will be significantly easier and less costly in the early stages. Turning a blind eye to it may result in the engine becoming irrevocably damaged.

Can an exhaust leak cause a misfire?

An exhaust leak can be the cause behind a misfire. However, it is not the lone reason for a misfire. An array of different things can be responsible for the engine misfiring. Engine noise, excess fuel consumption, gas smell are some indicators of an exhaust leak.

A misfire can be easily caused by a leak in the manifold exhaust. In cases like this, you will notice your engine making loud, whirring noises when accelerating or driving the car.

The leak in the exhaust manifold will most likely begin to release un-muffled gas through the leak which also attributes to the engine making loud noises.

Finally, the number of trips to the gas station will also increase because the misfire caused by the manifold exhaust leak will decrease fuel efficiency.

All that being said, sometimes the misfires can also be random and it is not necessary that the cause behind misfiring is a leak in the exhaust. Some random misfires in the engine can happen at idle.

Sometimes these random misfires are caused when the engine begins to pull too hard when it is under load and when the rpm is high during the throttle transitions while the air and fuel mixture is changing.

So, during these times a few random misfires will evidently occur and fortunately they don’t usually cause any major problems in performance or an increase in emissions.

How does an exhaust leak cause a misfire?

We already know by now that exhaust leaks, especially the leaks in the exhaust manifold can be the reason behind misfires.

The misfire usually occurs because the leak in the exhaust has a lot of effect on the motor as extra oxygen is able to enter the exhaust system due to the presence of the leak.

So, the accumulation of extra oxygen sends false reports to the oxygen sensors located in the rear of the exhaust system, the sensor detects a false increase in oxygen levels.

This false report then prompts the onboard computer of the car to start sending more fuel to the engine in an attempt to maintain the right mix of air and fuel that is required for combustion.

This causes the engine to get worn down at a much faster pace because of the increase in the amount of fuel burned during combustion. And as the engine continues to work overtime, problems arise in the pistons and fuel injectors.

Ultimately, due to the excessive amount of overuse and wear, the engine begins to misfire in response.

What are the symptoms of an exhaust leak?

An exhaust leak has a few symptoms. If the car owner is able to identify this and take care of the leak in due time, then it is possible to avoid the misfires that will inevitably take place because of the presence of the leak in the exhaust system.

In order to make it easier to identify these symptoms, we have listed below the most common ones.

Loud noise:

A common indicator of an engine leak is the loud noise it will begin to emit. Especially during accelatering, it will make a loud rumbling sound, followed by some popping and hissing sound when the car’s engine is running.

Loss of accelaration:

An engine leak can cause a loss of acceleration and power which will only keep decreasing if the engine leak is left untreated.

When this occurs the overall performance of the car engine will also subsequently fall. The car engine will not accelerate as smoothly when the gas pedal is stepped on.

Gas smell:

Sometimes an exhaust leak can be traced by the smell of gas fumes because once the exhaust system is damaged by a leak, it allows gas fumes to enter the passenger cabin area of the car.

Fuel consumption:

You will begin to need more fuel than before because once the exhaust leak causes a disruption in the balance between the air and fuel.

This causes the engine to run less efficiently which simultaneously decreases the entire engine’s efficiency.

If you begin to notice your car displaying these symptoms, it is best to avoid delaying and have the exhaust leak fixed as soon as possible to prevent further damage and misfires.

How to check for an exhaust leak?

If you suspect that your car engine has an exhaust leak but you do not want to take it to the mechanics. Here is an easy and inexpensive way to find the gas leak in your exhaust manifold right at home using products that are usually available in the house.

Attach blower:

Start by attaching a leaf blower or a vacuum to the exhaust exit, if the car has two exhaust exits, seal the other one with a plastic hand glove and tape it. Now, begin to blow cool air into the exhaust system to create a positive pressure.

Spray dish soap:

As cool air is blowing into the exhaust system, take a mixture of dish soap and water and fill a spray bottle with it.

Now, spray this generously on the exhaust system. Do not miss any spots. In a few seconds you will notice bubbles forming in the places with the leaks.

This is how easy it is to locate the leaks in the exhaust systems. You can try this process easily at home if you suspect your car has an exhaust leak.

What problems can exhaust leak cause?

Many people live under the misconception that an exhaust leak isn’t a serious problem. But the problems that stem from an exhaust leak can be extensive and also expensive. Some problems that accompany an exhaust leak are:

Dangerous fumes:

A good exhaust system is supposed to safely expel the toxic gas fumes released by the engine through the exhaust exit but exhaust leaks allow these fumes to enter the vehicle’s passenger cabin.

The high content of carbon monoxide in this gas fume can harm a person slowly if they breathe it in for prolonged periods of time.

Damage to the entire engine:

The engine produces a lot of heat when it is running, an exhaust system with a leak cannot get rid of it seamlessly through the exit exhaust, it instead gets released in the engine.

This excessive heat can end up damaging the important valves present in the engine and also cause other extensive internal engine damage that will be very costly to repair.

Catalytic convertor and O2 sensor failure:

As the exhaust leak attracts unnecessary oxygen into the system, this prevents the catalytic converter and O2 sensor from operating correctly and showing the accurate reading.

How much does it cost to fix an exhaust leak?

It can cost anywhere from $160 to $330 to get an exhaust leak fixed professionally. We need to take the time needed for this into consideration first, the repair can take two to three hours and most independent car shops will charge between $80 to $90 per hour which if you calculate will end up being either $160 to $270.

Car dealerships, on the other hand, will charge higher, say approximately $110 an hour. Therefore, you will be expected to pay a bill of around $220 to $330.

You can also fix an exhaust leak at home without welding if you know how to. In that case you will only pay for the material needed to seal up the leak, which are usually quite inexpensive and easily accessible.

Is it safe to drive with an exhaust leak?

It is neither a good idea nor is it safe to drive around in a car with an exhaust leak. The leak can cause substantial damage to the car’s engine and also cause a drop in fuel efficiency. All of this will only cost you more money the longer you leave the exhaust leak unfixed.

How long can I drive with an exhaust leak?

It depends on the leak but normally you should be able to drive about two weeks after the leak has formed.

However, the leak will continue to enlarge and make more noise which will end up attracting the attention of police officers. And they can give you a ticket for this offense. So, not only will you damage the engine but will also end up with a ticket.


An exhaust leak, especially if it is in the exhaust manifold, can cause a misfire. This is very dangerous for the car and the people inside the car. Therefore, the moment you become aware of the leak, it would be smart to locate the leak and have it fixed in record time.