6 Signs of an Exhaust leak (& how to fix it)

The exhaust system is intended to transfer exhaust fumes to your engine and back to the vehicle. It prevents passengers or drivers from inhaling harmful fumes. 

It’s also designed to carry the exhaust fumes to the vehicle’s rear as efficiently as possible.

What happens when it leaks? This article will explain the signs and costs of repairing an exhaust leak. Let’s look at the signs first.

A blowing sound coming from under your vehicle is the most obvious sign of an exhaust leak. Your exhaust sound may also become louder than usual if it’s a large leak. A check engine light or low engine performance may be visible on your dashboard.

While these are not all possible signs, it’s a good start. You can look at our list to see if your exhaust is leaking fumes. 

Below is a list that explains the most common symptoms associated with a leaking exhaust.

Exhaust leak symptoms

1. More Engine Sounds Than Normal

When your exhaust is leaking, the first sign you'll notice is a louder sound in your vehicle.

There will be one to two mufflers on your exhaust pipes that reduce the sound of your engine.

If the exhaust leak occurs before one of these mufflers – the sound will not be silenced by the mufflers because it will flow out before them. The extent of the exhaust leak will determine how loud it makes.

2. A booming sound comes from below

A small exhaust leak can cause a whistle sound to be heard as you rev your engine. It can make different noises depending on how large the exhaust leak is. In some cases it may even create high-pitched whistling sounds.

If you can hear a “blowing” sound from underneath your car and it wasnt there before – you do most likely have an exhaust leak.

3. Verify Engine Light

Modern cars have sensors in the exhaust to monitor the amount of fuel mixture that is emitted from their engines. These sensors also measure the effectiveness of the catalytic conversion. These sensors are also known as O2 Sensors or Oxygen Sensors.

If you have an exhaust leak before one of these sensors – it will cause them to measure faulty values, and the engine control unit will recognize this. The check engine light will appear on the dashboard.

4. High Engine Performance

Similar to the check engine light, this applies. If there's an exhaust leak in front of one these sensors, the sensor will return false data to the engine control unit.

The engine control unit will then use this information to calculate the air-fuel mixture of the next cycle in the car engine, and because the values are wrong – it will cause an even more strange air-fuel mixture. It can result in rough idle or slow acceleration as well as misfires.

It is time to check for an exhaust leak if the engine makes a more loud noise and the performance drops.

5. Unusual Odor

You can also smell the exhaust fumes if your engine is in use.

Your exhaust system was designed to stop this, as we have already stated. You will notice an unusual smell if your exhaust fails to contain fumes. 

Exhaust fumes can cause severe health problems for people who are exposed to them. You should immediately fix the exhaust fumes if you are able to smell them. 

6. Failure to pass emission tests

You must pass an emission test every year in certain countries or states. An exhaust leak on any part of the exhaust system can affect your emission test.

If the leak is before the O2 sensors, it will mess with the air-fuel mixture, and if the leak is after these – the emission test will show a too lean mixture, and you will fail the test, depending on the size of the exhaust leak.

Are Exhaust Leaks Safe for Driving? 

Because exhaust leaks can be harmful to the environment as well as your health, we don't recommend you drive around with them. Unlucky drivers may also be at risk of setting your car on fire.

The safety of the vehicle will depend greatly on what’s causing your exhaust leak. As already stated, exhaust fumes can be harmful if you’re exposed to them for a prolonged period of time. 

Sometimes, exhaust fumes get very hot. Unlucky people who have an exhaust leak in an unsuspected location can set your car on fire.

If you’re not sure, have your exhaust inspected by a professional as this can usually be carried out either free of charge or at very little cost.

The cost of exhaust leak repair

Average exhaust leak repair costs range from $100 to $800. This is heavily dependent on the source of the leak.

These are the typical repair costs for exhaust leak repairs. These costs include both labor and parts. It will depend on the car you drive.

Sometimes, you may be lucky and your exhaust leak can easily be repaired with a welding machine. If you are able to fix the problem yourself, this can be a great solution for your exhaust leak.

Many exhaust systems can easily be replaced without replacing the entire system. This allows for significant savings.

Catalytic converters and DPF’s are often on the more expensive side of the scale, so if you can fix your leak without replacing these, that’s always a bonus.