When you have owned a vehicle for quite some time now, it’s absolutely normal for some problems to pop up unexpectedly. While things like a busted tire, overheating engine, and worn-out brake pads have their own degrees of severity, there’s nothing more irritating than a pungent odor.

If one day you’ll find that it smells like rotten eggs inside your car, it’s a definite cause for concern. There are various issues associated with this odor, and you shouldn't delay in solving this particular issue.

As to what causes it, stick with us, and we’ll try to give a detailed answer.

The rotten egg smell is mainly associated with sulfur. If it comes from inside your car, it might be a cause of serious concern as fuel contains sulfur converted to a neutral-smelling compound during combustion and afterward in your car’s emission system. 

If your car smells of rotten eggs even after replacing the transmission oil, here are some common reasons for why it might be happening. 

A vehicle catalytic converter neutralizes emissions like hydrogen sulfide and harmless odor , preventing air pollution. A significant build-up of byproducts on the catalytic converter will cause it to overheat and emit a sulphuric smell in the car’s cabin. If it becomes clogged, unneutralized, harmful and intense sulfur gas will be released, and the only solution will be a total replacement. 

The fuel pressure sensor regulates the fuel flow in the engine. A faulty pressure sensor will allow too much oil to reach the catalytic converter. The malfunction in the catalytic converter will emit sulfuric gasses and make your car smell like rotten eggs. The first thing to do when you smell the odor in your car is to check the fuel filters and sensors. 

Transmission fluid lubricates the car’s gear system and should remain within the engine. If it’s no longer so and there’s a leak, you may smell the pungent odor. Changing the transmission fluid as frequently as the car manufacturer recommends and cleaning up the puddles should solve the problem. 

Your car might emit some other smells that might be a cause for concern. Sometimes there is a gaseous smell, and at other times, it might be a musty smell from the AC vents. It is essential to understand the various scents that the car emits to identify and troubleshoot the problem. 

If your car emits a rotten egg smell, there might be a problem with the catalytic converter, fuel pressure regulator, fuel filter, or even the old transmission fluid. Whatever the cause, if you get the rotten egg smell in your car, take your vehicle to the mechanic as soon as possible and resolve this problem. The mechanic will determine which part is at fault and repair or replace it before it affects other parts of the engine. If left unchecked, this issue can cause your car to break down in the middle of the road.

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© 2023 J.D.Power. All rights reserved.

© 2019 J.D.Power. All rights reserved.