Can Exhaust Leak Cause Misfire?

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can exhaust leak cause misfire

When your car has been diagnosed with an exhaust leak, you’re likely to have some unresolved concerns, like how the leak will influence the engine performance? Will it cause other issues such as engine misfire? Is it safe to drive? Though exhaust leaks vary in intensity, they nearly always cause one or even more symptoms. So if you don’t have it repaired, it might result in other issues with your car down the road.

Exhaust leak is one of the wide arrays of issues that might result in your engine misfiring. In most cases, exhaust leaks originate mostly in the exhaust manifold due to a faulty exhaust manifold gasket, the component that connects the engine to the exhaust system, the same manner with an intake manifold. An exhaust manifold leak might result in backfiring, decreased fuel efficiency by substantially increasing fuel delivery, and engine problems.

Continue reading, and we’ll discuss the consequences of an exhaust leak and the things you must do if your automobile is misfiring and how to resolve the issue by targeting the source of the issue.

How Can Exhaust Leak Cause Misfire?

A few instances of numerous engine cylinder misfires have been recorded due to an exhaust manifold gasket leak. Exhaust streams are essentially a sequence of pulses separated by pressure zones of low and high pressure. The component of the system that is under high pressure would leak to the outside. The exhaust pulse’s low-pressure part will suck in the air from the outside.

This extra outside air affects the oxygen sensor upstream. The Powertrain Control Module (PCM) receives a (false) lean condition and substantially increasing fuel delivery to that banks of cylinders. The resultant fuel mixture is thus too potent since the additional gasoline was unnecessary. The over-rich state then results in carbon fouling of the spark plugs causing misfires. A lean exhaust code and misfire codes are placed on the bank when there is an exhaust leak. 

For instance, On a V8 engine, one bank will have a super high fuel cut, while the other bank will have a standard fuel cut. The bank with high fuel trim will have multiple cylinders with misfire counts; this also affects your car’s fuel efficiency. Please always remember that this is a particular circumstance in which the exhaust leak occurs before the upstream O2 sensor. An exhaust leak that extends across the oxygen sensor would not produce this impact.

What Is An Engine Misfire?

Your automobile is propelled forward by gasoline that is precisely mixed with oxygen in the engine. Combustion occurs inside the cylinder, causing the pistons to push up and down, generating the energy required for motion. All cylinders must fire in precision for the engine to work correctly, one after the other. A misfiring engine occurs when the combustion reaction occurs at the incorrect moment.

Generally, an engine usually has between four and twelve cylinders. Additional cylinders are possible; several high-performance cars even feature sixteen. However, the most prevalent are four-cylinder, six-cylinder, and eight-cylinder engines. If one of the cylinders misfires, you will experience a decrease of power proportional to the cylinder’s exit from the combustion process. That implies that if one cylinder in four-cylinder engine misfires, 25% of the engine’s output is gone.

Another Issue Caused By Exhaust Leaks

Not only engine misfires are a terrible indicator of an exhaust leak. Indeed, a leak in the exhaust system may result in a slew of complications for your car. One of the most noticeable issues is excessive heat generated outside your engine. Exhaust leaks similar to those that lead engines to misfire may also enter open places beneath your hood. These burnt exhaust gases might harm the electrical components, such as wires, to overheat and melt.

The very same exhaust gases or fumes that could cause harm to your electrical components due to prolonged contact with heat can also create additional difficulties. There is a possibility that any escaping gases may reach the car’s cabin, where you and your passengers are. When this occurs due to exhaust fumes, you run the danger of contracting carbon monoxide, leading to toxic intoxication that might cause you to pass out while driving.

Other Symptoms Of An Exhaust Leak

Exhaust leak can cause harmful chemicals from the emissions to penetrate the cabin of your car, endangering the safety of everyone within. Since these lethal vapors are colorless and invisible, you will not notice or feel them. You’ll just breathe the fumes, which can make you uncomfortable and could possibly kill you.

That is why it is critical to identify the signs of a failing exhaust system and get it serviced as quickly as possible. The following are the most typical signs of an exhaust leak.

Noise Getting Louder

Whenever you start your car and notice a progressively loud noise emanating from the engine’s area, this is often a warning sign of an exhaust leak. Bear in mind that an exhaust manifold gasket separates the exhaust manifold from the engine block. This gasket, like the exhaust pipe, is continually heated and cooled.

Gas Pedal Vibrates

The automobile will tremble if there is even the slightest exhaust leak. However, if the leak is significant, the vibrations would also be substantial. You will first become aware of these vibrations emanating through the gas pedal. If nothing is done, vibrations might be sensed on the steering wheel. Eventually, these vibrations will be felt through the flooring.

Unusual Noise When Accelerating

Lay your foot on the gas pedal, then listen to any strange sounds. You almost certainly have a problem when you hear an excessively noisy engine and noises similar to air rushing or even whistling. However, most individuals have difficulty distinguishing between various engine noises, such as exhaust sounds, exhaust manifold leak, and a vacuum line leak. Not just that, but a variety of other engine issues might cause weird engine sounds.

Rough Idle

The sole reason an exhaust leak might produce a rough idle is when the leak was in a spot where it could penetrate the air intake system. The Exhaust Gas Recirculation ( EGR) Valves permit the reintroduction of burned exhaust gases into the intake manifold, resulting in a rich fuel condition by lowering the quantity of oxygen available. Also, a bad intake manifold gasket can cause rough idling and running. Moreover, if there is an exhaust leak before the catalytic converter and the O2 sensor, your car will have a rough idle.

Bad Fuel Efficiency

If you notice your fuel gauge indicating an almost empty gas tank, even though you just refueled. That is your car is consuming more gas than usual, it might result from an exhaust leak. Such leaks make it more difficult for your engine to function, making a negative impact, and decreased fuel efficiency.

Unusual Odor

Not every exhaust emissions are odorless; carbon monoxide is an exception. If your exhaust manifold leaks, you will smell a pungent stench within or outside your car. If the stench lingers, it is most likely dangerous exhaust fumes that you do not want to inhale for an extended period. Take your car to an auto repair shop immediately to have the issue repaired. Ensure that you are driving with your windows down.

Check Engine Light

An exhaust leak would almost certainly illuminate the check engine light as well since it might result in inaccurate oxygen O2 sensor readings.

Driving With A Misfiring Engine Cylinders

It’s not safe to drive your automobile if the engine is misfiring. If you detect an occasional lack of power or slow acceleration and poor engine performance, you should seek immediate assistance from a mechanic. There are plenty of threats involved with driving with a misfiring engine.

The loss of power and acceleration related to a misfired engine may be quite hazardous in intimate settings. If you must react swiftly to prevent an accident, this is no longer a choice. Consider what would occur if your acceleration is severely restricted and you wanted to avoid colliding with an approaching car. The more you run with a misfiring engine, the more prone you inflict further engine damage.

Avoid Engine Misfire

The most straightforward approach to prevent an engine misfiring problem is routine maintenance as specified in your owner’s handbook. Maintain your vehicle’s engine to manufacturer specifications. Additionally, an annual trouble-code scan performed by a properly equipped shop will identify any potential issues before they develop into major failures.

Exhaust Leak Repair Cost

The approximate cost of repairing an exhaust leak is often from $100 to $800. However, this relies on the severity and portion of the leak. The following summarizes the typical cost of exhaust leak correction. Below are the estimated rates include both parts and labor. This is highly dependent on your location and the make and model of your vehicle.

  • Catback Exhaust Replacement- $150 up to $600
  • Catalytic Converter Replacement – $400 up to $1500
  • Exhaust Joint Replacement – $30 up to $200
  • Whole Exhaust Pipe Replacement – $300 up to $1200
  • Front Exhaust pipe replacement – $150 up to $600
  • Exhaust Pipe Welding – $20 up to $100
  • Exhaust Braided Flex Pipe –$100 up to $300
  • Exhaust Manifold Repair – $570 up to $900


Yes! an exhaust system leak can cause your engine cylinders to misfire, as can plenty of other issues. If your engine fails due to misfires, the best treatment choice is to bring your automobile to a specialist for diagnostics. Once you’ve determined the reason, you’ll get a variety of alternatives for resolving the issue. Sadly, it could be pretty costly if your car suffers from an exhaust leak.


What problems can an exhaust leak cause?

An exhaust leak may allow harmful gases to escape the atmosphere without being appropriately handled, resulting in cabin odors and failed emissions testing. Most of these carcinogenic fumes are odorless, which means you will be unaware they are seeping into the passenger compartment.

Can an exhaust leak cause loss of power?

An exhaust leak might impair your engine’s performance. If the exhaust leak is not repaired, your car will keep losing power, and fuel economy is decreased. If you find yourself making frequent excursions to the petrol station, an exhaust leak may be to blame.

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