Q: Why Do Some Exhausts Smell Bad?

asked by on November 25, 2015

Why do some exhausts smell bad?

The most common reasons for an exhaust system to smell bad is the result of the thermal reaction that occurs within the catalytic converter. The temperatures inside catalytic converters run around 1200F to 1600F. The front substrate inside the catalytic converter is used to convert carbon monoxide (a byproduct of combustion) and hydrocarbons (unburned fuel) into carbon dioxide and water vapor. The rear substrate inside the catalytic converter reduces oxides of nitrogen into nitrogen and oxygen. The catalytic reaction between the fuel being used and the noble metals in the substrates creates the smell that you’re concerned about. This smell is significantly present on brand new catalytic converters when they light off for the first time. If you are noticing that the smell is becoming overwhelming, this could be an abnormal issue, and you may want to have the smell inspected to make sure there is not something unusual going on.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

i'm planning to buy a 2016 camaro LT 1 2.0 L with i-4 turbo engine. i did a test drive and its not making noise, Can i make my car

You can change the exhaust after the catalyst to a performance exhaust. This will give you more power and louder exhaust depending on the system you purchase. Some aftermarket sites will give you a soundbite of what the exhaust will...

Are Harmful Emissions Reduced by a Car's Exhaust System?

The automobile exhaust system has been around as long as the car itself. The purpose of the original exhaust system was to divert gases from the the combustion process away from the engine and operator. The purpose of today's exhaust...

Black smoke coming out from exhaust and it wont accelerate, there is no power

The black smoke indicates you have a rich fuel condition happening in your fuel intake system. This means that the fuel being supplied to the motor is too much in relation to the air supplied creating an imbalanced air/fuel ratio...

Related articles

Symptoms of a Bad or Failing EGR Cooler
Common signs include engine overheating, exhaust leaking, and the Check Engine Light coming on.
Symptoms of a Bad or Failing Exhaust Clamp
If your exhaust is noisy, loose, or failing an emissions test, you may need to replace an exhaust clamp.
How to Remove Dog Odors from Your Car
It isn’t unusual for dog owners to take their furry friends along for trips in the car. After all, a dog...